FIG. 4.

Effect of antioxidants on EGFR transactivation. Serum-starved VSMC were stimulated with 20 ng of PDGF-BB/ml for 5 min after pretreatment with 10 mM NAC or 10 mM Tiron for 60 min. (A) Cell lysates were immunoprecipitated with anti-EGFR and analyzed by immunoblotting, probed with 4G10 (upper panel), and reprobed with anti-EGFR (middle panel) or anti-PDGFβR (lower panel). IP, immunoprecipitated. IB, immunoblotted. (B) Relative tyrosine phosphorylation level of EGFR. Both NAC and Tiron significantly inhibited EGFR transactivation by PDGF. ∗, P < 0.001. (C) PDGFβR bound to EGFR. PDGFβR coimmunoprecipitated with EGFR significantly decreased after antioxidant treatment. ∗, P < 0.001.