FIGURE 5.

Inhibition of α5β1 integrin function by EGF is dependent on Rho/Rho kinase. A and B, A431 cells were pretreated for 6 h with the indicated amounts of cell-permeable C3 transferase (A) or the Rho kinase inhibitor Y27632 for 1 h (B) prior to adhesion to fibronectin with or without EGF (3 nm). Error bars indicate S.D. of triplicate samples for one of three representative experiments. C, A431 cells were stimulated with EGF (3 nm) for the designated times, and protein phosphorylation was assessed by Western blotting using specific antibodies to phospho-MCL2 (pMLC2) and phospho-ERK (pERK). Staining for total FAK served as a loading control. D, bands for phospho-MLC2 were quantified and normalized to FAK. Values are means ± S.D. of three separate experiments. E, A431 cells were pretreated for 1 h with a suboptimal concentration of Y27632 (2.5 μm) or PD184352 (0.5 μm). Cell adhesion to fibronectin was assayed as described in the legend to Fig. 1. Statistical analysis to determine significance was performed using Student's t test. **, p < 0.01; ***, p < 0.001. Error bars indicate S.D. of triplicate samples for one of three representative experiments.