Fig. 6. FN-mediated FAK tyrosine phosphorylation. (A) Serum-deprived F cells expressing WT or mutant L1106A ßPDGFR were plated on FN-coated cell culture plates for the indicated times. Cell lysates were prepared and analyzed for either FAK Y397 phosphorylation or total FAK tyrosine phosphorylation (4G10). The same blots were detected with a polyclonal FAK antibody to assess FAK levels. An immunoblot representating three independent experiments shows decreased total tyrosine phosphorylation of FAK in cells expressing the mutant L1106A. (B) Quantitative comparison of FAK Y397 and total tyrosine phosphorylation from F cells expressing WT or the mutant L1106A ßPDGFR. Values were obtained from laser scanning densitometry and indicate the relative mean±s.d. from band intensities normalized to total FAK protein of three independent experiments. The asterisk indicates statistical significance (P<0.05).