Of Cell Types (of + cell_type)

Distribution by Scientific Domains

Kinds of Of Cell Types

  • variety of cell type


  • Selected Abstracts


    Ci-GATAa, a GATA -class gene from the ascidian Ciona intestinalis: Isolation and developmental expression

    DEVELOPMENTAL DYNAMICS, Issue 1 2003
    Palmira D'Ambrosio
    Abstract Members of the GATA family of zinc finger transcription factors have been shown to play important roles in controlling gene expression in a variety of cell types in many metazoan. Here, we describe the identification of Ci-GATAa, a member of this gene family, in the ascidian Ciona intestinalis. Whole-mount in situ hybridization showed that Ci-GATAa was expressed in a highly dynamic manner. The maternal transcript was evenly distributed in the embryo during early stages of development; however, the signal gradually decreased until it disappeared at the 64-cell stage. A zygotic transcript was detected at the 110-cell stage in the blastomeres precursors of three different tissues (brain vesicle, mesenchyme, and trunk lateral cells) and the signal was conserved in these territories up to the larval stage, indicating an important role for Ci-GATAa during ascidian differentiation. © 2002 Wiley-Liss, Inc. [source]


    Metalloproteinase expression in normal and malignant oral keratinocytes: stimulation of MMP-2 and -9 by scatter factor

    EUROPEAN JOURNAL OF ORAL SCIENCES, Issue 4 2000
    J. H. Bennett
    Matrix metalloproteinases (MMPs) are Zn2+ dependent proteases produced by a variety of cell types. They have a fundamental role in tissue remodelling, tumour invasion and metastasis. Scatter factor (SF), secreted by fibroblasts, has a paracrine action on epithelial cells and binds the trans-membrane c-met receptor inducing loss of adhesion, cell motility and invasiveness in vitro. The purpose of this study was to test if SF can regulate the production of MMPs by epithelial cells. Supernatants from oral squamous cell carcinoma-derived cells (H375 and H376), a human keratinocyte line (UP), and primary cultures of oral mucosal keratinocytes, grown in the presence or absence of SF, were analysed using 0.1% gelatin zymography. MMPs were characterised by comparison with human recombinant enzymes and by the use of specific inhibitors. Oral mucosal keratinocytes, UP, and H357 cells expressed MMP-2 and MMP-9, whilst H376 cells only expressed MMP-2. SF increased the expression of MMP-9 in UP and MMP-2 in H376 supernatants. Both MMP-2 and MMP-9 activity were increased in H357 and normal keratinocyte supernatants. This could be blocked using a human recombinant anti-SF antibody. In all epithelial lines tested, c-Met, the cell surface receptor for SF, could be detected. The results indicate that SF stimulates MMP expression in UP, H376, H357, and normal oral mucosal cells and points to a role for SF in the regulation of oral keratinocyte behaviour in wound healing and neoplasia. [source]


    Death-associated protein kinase (DAPK) and signal transduction: blebbing in programmed cell death

    FEBS JOURNAL, Issue 1 2010
    Miia Bovellan
    Death-associated protein kinase (DAPK) regulates many distinct signalling events, including apoptosis, autophagy and membrane blebbing. The role of DAPK in the blebbing process is only beginning to be understood and, in this review, we will first summarize what is known about the cytoskeletal proteins and signalling cascades that participate in bleb growth and retraction and then highlight how DAPK integrates with these processes. Membrane blebs are quasispherical cellular protrusions that have a lifetime of approximately 2 min. During expansion, blebs are initially devoid of actin, although actomyosin contractions provide the motive force for growth. Once growth slows, an actin cortex reforms and actin-bundling and contractile proteins are recruited. Finally, myosin contraction powers bleb retraction into the cell body. Blebbing occurs in a variety of cell types, from cancerous cells to embryonic cells, and can be seen in cellular phenomena as diverse as cell spreading, movement, cytokinesis and cell death. Although the machinery that executes this is still undefined in detail, the conservation of blebbing phenomenon suggests a fundamental role in metazoans and DAPK offers a door to further dissect this fascinating process. [source]


    Suppression of urokinase receptor expression by bikunin is associated with inhibition of upstream targets of extracellular signal-regulated kinase-dependent cascade

    FEBS JOURNAL, Issue 16 2002
    Hiroshi Kobayashi
    Our laboratory showed that bikunin, a Kunitz-type protease inhibitor, suppresses 4,-phorbol 12-myristate 13-acetate (PMA)- or tumor necrosis factor-alpha (TNF,)-induced urokinase-type plasminogen activator (uPA) expression in different cell types. In addition to its effects on protease inhibition, bikunin could be modulating other cellular events associated with the metastatic cascade. To test this hypothesis, we examined whether bikunin was able to suppress the expression of uPA receptor (uPAR) mRNA and protein in a human chondrosarcoma cell line, HCS-2/8, and two human ovarian cancer cell lines, HOC-I and HRA. The present study showed that (a) bikunin suppresses the expression of constitutive and PMA-induced uPAR mRNA and protein in a variety of cell types; (b) an extracellular signal-regulated kinase (ERK) activation system is necessary for the PMA-induced increase in uPAR expression, as PD098059 and U0126, which prevent the activation of MEK1, reduce the uPAR expression; (c) bikunin markedly suppresses PMA-induced phosphorylation of ERK1/2 at the concentration that prevents uPAR expression, but does not reduce total ERK1/2 antigen level; (d) bikunin has no ability to inhibit overexpression of uPAR in cells treated with sodium vanadate; and (e) we further studied the inhibition of uPAR expression by stable transfection of HRA cells with bikunin gene, demonstrating that bikunin secretion is necessary for inhibition of uPAR expression. We conclude that bikunin downregulates constitutive and PMA-stimulated uPAR mRNA and protein possibly through suppression of upstream targets of the ERK-dependent cascade, independent of whether cells were treated with exogenous bikunin or transfected with bikunin gene. [source]


    Roles of oxidized low-density lipoprotein and its receptors in the pathogenesis of atherosclerotic diseases

    GERIATRICS & GERONTOLOGY INTERNATIONAL, Issue 4 2002
    Noriaki Kume
    In elderly populations, atherosclerotic diseases, including ischemic heart disease and stroke, frequently impair quality of life and affect mortality. Hypercholesterolemia, especially increased plasma low-density lipoprotein (LDL), is one of the strongest risk factors for atheroscletorotic diseases. Oxidative modification of LDL appears to convert LDL particles to more atherogenic forms. Scavenger receptor class A (SR-A) and CD36 have been identified and well-characerized as receptors for Ox-LDL in macrophages. In addition to these molecules, lectin-like oxidized LDL receptor (LOX)-1 and scavenger receptor for phosphatidylserine and oxidized lipoprotein (SR-PSOX) are type II and I membrane glycoproteins, respectively, both of which can act as cell-surface endocytosis receptors for atherogenic oxidized LDL (Ox-LDL). LOX-1 expression can dynamically be induced by pro-inflammatory stimuli, and is detectable in cultured macrophages and activated vascular smooth muscle cells (VSMC), in addition to endothelial cells. LOX-1-dependent uptake of Ox-LDL induces apoptosis of cultured VSMC. In vivo, endothelial cells that cover early atherosclerotic lesions, and intimal macrophages and VSMC in advanced atherosclerotic plaques dominantly express LOX-1. LOX-1 expressed on the cell-surface can be cleaved in part and released as soluble molecules, suggesting the diagnostic value of soluble LOX-1. SR-PSOX is a newly identified receptor for Ox-LDL, which appears to be identical to CXCL16, a novel membrane-anchored chemokine directed to CXCR6-positive lymphocytes. In contrast to LOX-1, which is expressed by a variety of cell types, SR-PSOX expression appeared relatively confined to macrophages in atherogenesis. Taken together, oxidized LDL receptors, including LOX-1 and SR-PSOX, may play important roles in atherogenesis and atherosclerotic plaque rupture. [source]


    Schwann cell caveolin-1 expression increases during myelination and decreases after axotomy

    GLIA, Issue 3 2002
    Daniel D. Mikol
    Abstract The caveolins are a family of related proteins that form the structural framework of caveolae. They have been implicated in the regulation of signal transduction, cell cycle control, and cellular transport processes, particularly cholesterol trafficking. Caveolin-1 is expressed by a variety of cell types, including Schwann cells, although its expression is greatest in differentiated cell types, such as endothelial cells and adipocytes. In the present work, we characterize caveolin-1 expression both during rat sciatic nerve development and after axotomy. Schwann cells express little caveolin-1 on postnatal days 1 and 6. By P30, myelinating Schwann cells express caveolin-1, which is localized in the outer/abaxonal myelin membranes as well as intracellularly. After axotomy, Schwann cell caveolin-1 expression in the distal nerve stump decreases as Schwann cells revert to a premyelinating (p75-positive) phenotype; residual caveolin-1 within the nerve largely localizes to myelin debris and infiltrating macrophages. We speculate that caveolin-1 plays a role in the biology of myelinating Schwann cells. GLIA 38:191,199, 2002. © 2002 Wiley-Liss, Inc. [source]


    Sulphasalazine inhibits macrophage activation: inhibitory effects on inducible nitric oxide synthase expression, interleukin-12 production and major histocompatibility complex II expression

    IMMUNOLOGY, Issue 4 2001
    György Haskó
    Summary The anti-inflammatory agent sulphasalazine is an important component of several treatment regimens in the therapy of ulcerative colitis, Crohn's disease and rheumatoid arthritis. Sulphasalazine has many immunomodulatory actions, including modulation of the function of a variety of cell types, such as lymphocytes, natural killer cells, epithelial cells and mast cells. However, the effect of this agent on macrophage (M,) function has not been characterized in detail. In the present study, we investigated the effect of sulphasalazine and two related compounds , sulphapyridine and 5-aminosalicylic acid , on M, activation induced by bacterial lipopolysaccharide (LPS) and interferon-, (IFN-,). In J774 M, stimulated with LPS (10 µg/ml) and IFN-, (100 U/ml), sulphasalazine (50,500 µm) suppressed nitric oxide (NO) production in a concentration-dependent manner. The expression of the inducible NO synthase (iNOS) was suppressed by sulphasalazine at 500 µm. Sulphasalazine inhibited the LPS/IFN-,-induced production of both interleukin-12 (IL-12) p40 and p70. The suppression of both NO and IL-12 production by sulphasalazine was superior to that by either sulphapyridine or 5-aminosalicylic acid. Although the combination of LPS and IFN-, induced a rapid expression of the active forms of p38 and p42/44 mitogen-activated protein kinases and c-Jun terminal kinase, sulphasalazine failed to interfere with the activation of any of these kinases. Finally, sulphasalazine suppressed the IFN-,-induced expression of major histocompatibility complex class II. These results demonstrate that the M, is an important target of the immunosuppressive effect of sulphasalazine. [source]


    Rapid denaturing high-performance liquid chromatography (DHPLC) for mutation scanning of the transforming growth factor ,3 gene using a novel proof-reading polymerase

    INTERNATIONAL JOURNAL OF IMMUNOGENETICS, Issue 5 2003
    A. Bayat
    Summary We have utilized a novel variation on the conventional denaturing high-performance liquid chromatography (DHPLC) technology, which we term rapid DHPLC, combining changes in instrumentation, cartridge technology and analysis conditions to enable significant increases in throughput to be achieved. In addition, the use of a novel proof-reading polymerase for sample amplification with a low misincorporation rate enables simplification of the DHPLC patterns and hence enhanced mutation detection recognition. This scheme for increasing DHPLC throughput has been tested by scanning the transforming growth factor (TGF) ,3 gene for the presence of mutations for which there is limited published or on-line data available regarding the presence of gene polymorphisms. TGF, isoforms have multiple roles in cell division, growth, proliferation, transformation and differentiation. TGF,3 is a TGF, cytokine isoform, and has an important role in embryogenesis, cell differentiation and wound healing. The TGF,3 gene consists of seven exons and six introns spanning 43 000 bp of the human genome on chromosome 14q23,24. The rapid DHPLC approach enabled scanning of all seven exons and part of the promoter region (1000 bp upstream from exon 1 in the 5,-flanking regions) of the TGF,3 gene in 95 Caucasian individuals in only 8 days, in comparison to the 17 days it would have previously taken. Mutations were clearly identified in the promoter region of the TGF,3 gene but were absent from the exonic regions. Understanding the genetic variations affecting the TGF,3 gene is important as this molecule has multiple regulatory functions on a variety of cell types. [source]


    Tumor stroma fosters neovascularization by recuitment of progenitor cells into the tumor bed

    JOURNAL OF CELLULAR AND MOLECULAR MEDICINE, Issue 4 2006
    Ruth Ganss
    Abstract The tumor stroma is an active player during carcinogenesis and contains a variety of cell types such as vascular cells, fibroblasts and inflammatory cells which directly or indirectly foster neovascularization. During tumor progression stromal cells, in particular the neovasculature, acquire new characteristics distinct from their normal counterparts and display a high degree of plasticity to meet the tumor's demands. The local environment may, to some extent, shape pre-existing, tumor-resident stromal cells. However, there is accumulating evidence that new endothelial and other stromal cells are actively recruited into tumors, and that this recruitment is essential for a unique and tumor-specific proangiogenic environment. [source]


    Understanding immune cell trafficking patterns via in vivo bioluminescence imaging

    JOURNAL OF CELLULAR BIOCHEMISTRY, Issue S39 2002
    Stefanie Mandl
    Abstract Cell migration is a key aspect of the development of the immune system and mediating an immune response. There is extensive and continual redistribution of cells to different anatomic sites throughout the body. These trafficking patterns control immune function, tissue regeneration, and host responses to insult. The ability to monitor the fate and function of cells, therefore, is imperative to both understanding the role of specific cells in disease processes and to devising rational therapeutic strategies. Determining the fate of immune cells and understanding the functional changes associated with migration and proliferation require effective means of obtaining in vivo measurements in the context of intact organ systems. A variety of imaging methods are available to provide structural information, such as X-ray CT and MRI, but only recently new tools have been developed that reveal cellular and molecular changes as they occur within living animals. We have pioneered one of these techniques that is based on the observations that light passes through mammalian tissues, and that luciferases can serve as internal biological sources of light in the living body. This method, called in vivo bioluminescence imaging, is a rapid and noninvasive functional imaging method that employs light-emitting reporters and external photon detection to follow biological processes in living animals in real time. This imaging strategy enables the studies of trafficking patterns for a variety of cell types in live animal models of human biology and disease. Using this approach we have elucidated the spatiotemporal trafficking patterns of lymphocytes within the body. In models of autoimmune disease we have used the migration of "pathogenic" immune cells to diseased tissues as a means to locally deliver and express therapeutic proteins. Similarly, we have determined the tempo of NK-T cell migration to neoplastic lesions and measured their life span in vivo. Using bioluminescence imaging individual groups of animals can be followed over time significantly reducing the number of animals per experiment, and improving the statistical significance of a study since changes in a given population can be studied over time. Such rapid assays that reveal cell fates in vivo will increase our basic understanding of the molecular signals that control these migratory pathways and will substantially speed up the development and evaluation of therapies. J. Cell. Biochem. Suppl. 39: 239,248, 2002. © 2002 Wiley-Liss, Inc. [source]


    Fibroblast growth factor receptor-3 null mice exhibit a delay in the development of oligodendrocytes and myelination

    JOURNAL OF NEUROCHEMISTRY, Issue 2002
    R. Bansal
    Fibroblast growth factors (FGFs) comprise of a family of twenty-three members which bind to four receptor tyrosine kinases (R1,R4). They induce a broad spectrum of biological effects in a variety of cell types, including neurons and glia in the CNS. In oligodendrocytes (OLs), FGF-2 elicits a number of specific responses depending on their stage of development. During OL development in vitro, the expressions of FGF-receptor mRNAs are differentially regulated. R1 mRNA increases gradually along with OL maturation, whereas R3 and R2 mRNAs peak at the OL progenitor and mature OL stages, respectively, suggesting a differential roles of these receptors in OL development. R3 is also expressed by astrocytes. To determine the roles of R3 during OL development and myelination in vivo, we have employed mice lacking functional R3 (R3-null). During myelination (P7, P9, P13), reduced numbers of differentiated OLs and myelinated fibers are observed in the brains of R3 null mice compared to wild type mice. Moreover, up-regulation of glial fibrillary acidic protein-positive astrocytes is found in the cerebellum and spinal cord of R3 null mutants. However, the number of OL progenitors (PDGF-Ra), BrdU incorporation, and cell survival (TUNEL assay) are all comparable, and R3-null myelin in adult mice appears to be similar to that of wild type mice. In mixed primary cultures of post-natal R3 null brain (that have few if any neurons), OLs exhibit a delay in differentiation similar to that observed in vivo. In summary, our results elucidate regulatory roles of FGF-R3 in mouse brain, in particular with regard to its roles in the timing of OL maturation and myelin formation (MS Society, Canada, NIH NS38878-03). [source]


    Inhibitory Effects of Ethanol on Rat Mesangial Cell Proliferation via Protein Kinase C Pathway

    ALCOHOLISM, Issue 3 2002
    Kayoko Segawa
    A large body of evidence has shown that ethanol inhibits the cell growth and cell proliferation in a variety of cell types. However, it has not been studied whether ethanol inhibits the proliferation of mesangial cells (MC) in the kidney. We examined the effects of ethanol on cell proliferation in cultured rat MC. Treatment with ethanol (10,200 mM) for 48 hr inhibited [3H]thymidine incorporation into MC in a concentration-dependent manner. The same concentrations of ethanol also inhibited the increase in cell number of MC. GF109203X and chelerythrine chloride, inhibitors for protein kinase C, eliminated the inhibitory effects of ethanol; and protein kinase C activator, PMA, mimicked the effects of ethanol. In contrast, neither the protein kinase A inhibitor H-89 nor the protein kinase G inhibitor KT5823 had any effect. These findings suggest that ethanol has inhibitory effects on the proliferation of MC, probably via activation of the protein kinase C pathway. [source]


    A link between the interleukin-6/Stat3 anti-apoptotic pathway and microRNA-21 in preimplantation mouse embryos

    MOLECULAR REPRODUCTION & DEVELOPMENT, Issue 9 2009
    Xing-Hui Shen
    Signal transducers and activators of transcription-3 (Stat3) plays a central role in interleukin-6 (IL-6)-mediated cell proliferation by inhibiting apoptosis in a variety of cell types. MicroRNA-21 (miRNA-21), a ubiquitous miRNA, acts as an anti-apoptotic factor that seems to be indirectly but strictly linked to Stat3. In order to determine whether the IL-6 induced Stat3 anti-apoptosis pathway is linked with miRNA-21, we first determined the effects of recombinant mouse IL-6 on Stat3 expression, mouse embryo viability, and the mRNA levels of apoptosis related genes and miRNA-21 during mouse embryo development in vitro. Addition of 10 or 100,ng/ml of recombinant IL-6 to the culture medium did not affect the developmental ability of 2-cell stage embryos into blastocysts. However, total cell number was significantly increased and apoptosis was reduced in blastocyst stage embryos cultured in the presence of 100,ng/ml of recombinant IL-6. Furthermore, addition of recombinant IL-6 to the culture medium significantly increased the copy numbers of anti-apoptotic miRNA-21, up-regulated Bcl2l1, and down-regulated casp3. Similarly, the injection of mature miRNA-21 into cells up-regulated Bcl2l1 and down-regulated casp3. These results suggest that the induction of the Stat3 anti-apoptotic pathway by IL-6 is linked to miRNA-21 expression, which possibly results in the regulation of cell apoptosis in early mouse embryo development. Mol. Reprod. Dev. 76: 854,862, 2009. © 2009 Wiley-Liss, Inc. [source]


    An optimum method designed for 2-D DIGE analysis of human arterial intima and media layers isolated by laser microdissection

    PROTEOMICS - CLINICAL APPLICATIONS, Issue 10 2009
    Fernando de la Cuesta
    Abstract The formation and progression of atherosclerotic lesions involve complex mechanisms which are still not fully understood. A variety of cell types from the distinct arterial layers are implicated in the whole process from lipid accumulation within the vascular wall to plaque development and final rupture. In the present work, we employ the combination of laser microdissection and pressure catapulting and 2-D DIGE saturation labeling to investigate the human intima and media sub-proteomes isolated from atherosclerotic (coronary and aorta) or non-atherosclerotic vessels (preatherosclerotic coronary arteries). Laser microdissection and pressure catapulting allows the specific isolation of regions of interest. In turn, DIGE saturation labeling overcomes the limitation of extensive microdissection times to recover the protein amount required to perform comparative 2-DE, particularly when dealing with tissue regions rich in myofilament proteins, which result in low protein recovery. The compatibility and optimum performance of both techniques were investigated in detail, paying special attention to tissue staining and protein solubilization. Since scarce amount of protein obtained from microdissected tissue made it impossible to directly perform protein identification from 2-DE spots by MS, we performed in-solution digestion followed by LC-MS/MS analysis of total protein extracts from intima and media in order to get an overall picture of protein composition. Proteins so identified confirm the nature of the isolated regions. Finally, similar spot resolution on 2-D DIGE gels was obtained for the different human artery types (coronary, aorta) and studied layers (intima, media), setting the basis for future clinical comparative studies. [source]


    Detection and analysis of mammary gland stem cells,

    THE JOURNAL OF PATHOLOGY, Issue 2 2009
    J Stingl
    Abstract Emerging evidence from a variety of tissue types, including the mammary gland, suggests that normal stem and progenitor cells are the likely targets for malignant transformation, and that these transformed cells can function as cancer stem cells that drive tumour growth. In order to develop therapies that target these cancer stem cells, it is essential to determine the molecular mechanisms that regulate the growth and differentiation of these cells and their normal counterparts. To this end, a number of quantitative robust clonal assays have been developed that can detect the presence of human and mouse mammary stem and progenitor cells. These assays, when used in conjunction with cell-sorting strategies, have permitted the prospective isolation and characterization of a variety of cell types, including stem cells. Evidence to date indicates that these stem cells exhibit properties of basal mammary cells, possess extensive self-renewal properties, and are capable of generating a large number of phenotypically-distinct progenitor cells, many of which display characteristics of luminal cells. This review article will focus on the assays used to detect mammary stem and progenitor cells, some of the properties of these cells and their progeny and how they relate to the cancer stem cells that drive breast tumour growth. Copyright © 2008 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd. [source]


    The Role of the Bcl-3 Proto-Oncogene in Thyroid Hormone-Induced Liver Cell Proliferation

    ARTIFICIAL ORGANS, Issue 6 2009
    Raza Malik
    Abstract The aim of the study was to determine if thyroid hormone-induced liver cell proliferation occurs through the Bcl-3 proto-oncogene. Rodents (including Bcl-3 knockout mice and the wild-type strain) were injected with a single dose of tri-iodothyronine (T3) and sacrificed at various time points. Hepatic mRNA (real-time polymerase chain reaction ) and protein expression (Western analysis) of Bcl-3 was quantified in rats stimulated with T3. Cell proliferation was induced in a variety of cell types after T3 injection at 24 h including hepatocytes (7 ± 1.1% vs. 0.45 ± 0.025%; P < 0.01), hepatic nonparenchymal cells (3.8 ± 1.2% vs. 0.3 ± 0.01%; P < 0.01), renal tubular cells (8.1 ± 1.6% vs. 0.2 ± 0.035%; P < 0.01), and splenic lymphocytes (4.8 ± 1.2% vs. 0.35 ± 0.02%; P < 0.01). We showed a twofold increase in hepatic Bcl-3 mRNA (P < 0.01) and protein expression (P < 0.01) at 24 h in rats stimulated with T3. However, there were no differences in the rate of liver cell proliferation between Bcl-3 knockout mice and the wild-type strain (0.4 ± 0.15% vs. 0.3 ± 0.1%), indicating that Bcl-3 was not functionally involved in thyroid hormone-induced liver cell proliferation. A single gene is unlikely to initiate the process of thyroid hormone-induced cell proliferation. A complex interaction between the genomic and nongenomic effects of thyroid hormone is likely to regulate the mitogenic effects. [source]


    Inhibitory effect of c-Met mutants on the formation of branching tubules by a porcine aortic endothelial cell line

    CANCER SCIENCE, Issue 12 2006
    Marino Maemura
    The association of hepatocyte growth factor (HGF) with its high-affinity receptor (c-Met) has been shown to induce mitogenesis, motogenesis and morphogenesis in a variety of cell types. Various point mutations in c-Met have been identified in hereditary and sporadic papillary renal carcinomas as well as in other carcinomas. In the present study, we examined the effects of c-Met point mutations on the morphology of a porcine aortic endothelial (PAE) cell line. When cultured in three-dimensional collagen gel, PAE cells formed branching tubule structures, and HGF treatment caused breakdown of the structures and induced a scattered morphology. The exogenous expression of c-Met point mutants inhibited the formation of tubules. HGF treatment induced the formation of tubules by PAE cells expressing some c-Met mutants, but it induced the scattering of PAE cells expressing other c-Met mutants. The presence of a low concentration of a mitogen-activated protein kinase/extracellular signal-regulated kinase kinase (MEK) inhibitor cancelled the inhibitory effect of the c-Met point mutations on the formation of tubules. These results suggest that c-Met point mutations affect the extracellular signal-regulated kinase (ERK) signaling required for the formation of tubules by PAE cells, and HGF binding changes the conformation of c-Met mutants, leading to the different signals required for formation of tubules and cell scattering. (Cancer Sci 2006; 97: 1343,1350) [source]