Figure 10.

Up-regulation of integrin β1 and fibronectin expression by EGF. Requirement of MEK/ERK pathway activation. (A) Northern blot analysis of integrin β1 subunit expression in hepatocytes stimulated (+) or not (−) by EGF in presence (+) or absence (−) of MEK inhibitor. When required, EGF and PD98059 were added at cell seeding and hepatocytes were harvested and analyzed at the indicated times after plating. (B) Western blot analysis of integrin β1 subunit expression in hepatocytes stimulated or not by EGF in presence or absence of MEK inhibitor and analyzed at the indicated times after plating. (C) Kinetics of the fibronectin expression in EGF- and/or PD98059-treated hepatocytes was performed at the indicated times. Normalization was done with actin primers. (D) Partial inhibition of hepatocyte spreading by addition of anti-integrin β1 subunit antibody. Hepatocytes were stimulated at seeding with EGF in the presence of antibody against β1 integrin or isotypic control and analyzed at the indicated times after plating. Bar, 120 μm. (E) Western blot of cyclin D1 expression in EGF-stimulated hepatocytes cultured in the presence of β1 integrin antibody (β1) or isotypic antibody control (iso), at the indicated times after seeding. These data are representative of three different experiments.