Fig. 1. Static stretch activates the p38, ERK1/2 and JNK MAPKs, as well as AKT. C2C12 myoblasts were seeded in six-well Bioflex® plates and allowed to proliferate to 85% confluence. Stretch was conducted in fresh growth medium for the indicated time periods. Time-matched, non-stretched myoblasts were used as controls. Whole cell extracts of myoblasts were prepared and analyzed by western blotting using antibodies against the phosphorylated form of (A) p38 (43 kDa), (C) ERK1/2 (42/44 kDa), (B) JNK (46/54 kDa) and (D) AKT (60 kDa). Total levels of the kinases were also monitored by western blot analysis. Representative blots from three independent experiments are shown. Arrows indicate bands of phosphorylated JNK. The optical density (OD) of corresponding bands, detected by western blot, was measured and analyzed with the paired t-test, by comparison of stretched samples with time-matched controls (n3). ^* indicates a statistical significance at P<0.01.