Fig. 2. Effect of selective inhibitors on the p43-ERK phosphorylation induced by oxidative stress. Protein (50 µg) from hearts perfused with 30 µmol l^-1 H₂O₂ for 5 min in the absence or presence of 25 µmol l^-1 PD98059 or 1 µmol l^-1 SB203580 was assessed by immunoblot using phosphospecific anti-ERK (A, top panel) or total (phosphorylation state independent) anti-ERK antibody (A, bottom panel). Blots are representative of three independent experiments. (B) Densitometric analysis of phospho-p43-ERK bands by laser scanning. Results are means ± S.E.M. for three independent experiments. ^*P<0.05 vs control value.