Fig. 1. Western blots showing dose–response (A) and time course (B) of p38-MAPK, MAPKAPK2 and Hsp27 phosphorylation in the amphibian heart after CoCl₂ treatment. (Ai) Phospho-p38-MAPK was detected in extracts (50 µg of protein) from control hearts (C) or hearts perfused for 15 min with the indicated concentration of CoCl₂. (Aii) Phospho-MAPKAPK2 was detected in identical samples. (Aiii) Phospho-Hsp27 was detected in identical samples. An anti-actin antibody was used as a control for equal protein loading (Aiv). (Bi) Phospho-p38-MAPK was detected in extracts (50 µg of protein) from control hearts (C) or hearts perfused with 500 µmol l^-1 CoCl₂ for increasing periods of time. (Bii) Phospho-Hsp27 was detected in identical samples. An anti-actin antibody was used as a control for equal protein loading (Biii). (C–G) Densitometric analysis of phospho-p38 (C,F), phospho-MAPKAPK2 (D) and phospho-Hsp27 (E,G) bands was performed by laser scanning. Western blots shown are representative of at least three independent experiments; data are means ± s.e.m. for at least three independent experiments. ^*P<0.001 and P<0.05 vs control (untreated) hearts.