FIG. 5.

Effect of Src family kinase inhibitor on EGFR transactivation. Serum-starved VSMC were pretreated with 1 μM PP2 for 30 min, followed by stimulation with 20 ng of PDGF-BB/mi or 10 ng of EGF/ml for 5 min. (A) Cell lysates were immunoprecipitated with anti-PDGFβR (left panel) or anti-EGFR (right panel) and analyzed by immunoblotting with 4G10 as the probe. (B) Cell lysates were immunoblotted with anti-phospho-Src (Y416) and reprobed with anti-Src. (C) Cell lysates were immunoprecipitated with anti-EGFR, analyzed by immunoblotting with 4G10 as the probe (upper panel), and reprobed with anti-EGFR (middle panel) or anti-PDGFβR (lower panel) antibody. IP, immunoprecipitated. IB, immunoblotted. (D) Relative tyrosine phosphorylation level of EGFR. PP2 significantly inhibited EGFR transactivation by PDGF. †, P < 0.005. (E) PDGFβR bound to EGFR. The PDGFβR coimmunoprecipitated with the EGFR significantly decreased after antioxidant treatment. †, P < 0.005.