Figure 2

Differential p70S6K stretch response in C57 and γ-SG^-/-primary cultures. Primary myotubes from C57 and γ-SG^-/- FDB fibers were cultured on silicone membranes and subjected to passive stretching for 30 min. Lysates were harvested 1, 2, or 4 h after stretch. (A) Representative images of i, satellite cells migrating from an FDB fiber and ii, differentiated myotubes. (B) Representative immunoblot for P-p70S6K (T389 site), P- and T-ERK1/2, P-FAK, P-Akt, T-Akt, and GAPDH in non-stretched (C) and stretched (1 h, 2 h, 4 h) primary cultures. (C-G) Quantification of activation levels. Legend in C applies to all graphs. P-ERK1 and 2 were normalized to T-ERK1 and 2, respectively, P-Akt was normalized to T-Akt and P-p70S6K and P-FAK were normalized to GAPDH. n = 3 (p70S6K) or 4 (all other proteins) independent sets of primary cultures per genotype. Bars represent mean ± standard error. Statistical significance was tested by two-way ANOVA.