FIG. 6.

Effect of receptor kinase inhibitors and antioxidants on ERK1/2 activity. Serum-starved VSMC were stimulated with 20 ng of PDGF-BB/ml after pretreatment with 1 μM AG1295 or 10 μM AG1478 for 30 min (A) or with 10 mM NAC or Tiron for 60 min or 1 μM PP2 for 30 min (B). Twenty micrograms of cell lysate was loaded onto each lane and analyzed by immunoblotting with anti-phospho-ERK1/2 antibody as the probe. Lower panels show the relative phosphorylation levels of ERK1/2. Each agent significantly inhibited ERK1/2 phosphorylation induced by PDGF stimulation. ∗, P < 0.001; †, P < 0.005; ‡, P < 0.01.