FIGURE 6.

Effects of 4-h stretch on colon-26 (C26) conditioned media-induced myotube signaling pathways. (A) Experiment overview: C2C12 myoblasts are plated on in growth media (GM); after 48 h at ∼85% confluence, differentiation media is added, which corresponds to day 0. At day 5 of differentiation, conditioned media (CM; GM or C26 + GM) is diluted with 50% serum-free DMEM and added to wells for 48 h. Myotubes are either left unstretched (0%) or stretched 5% in the last 4 h of CM incubation. Immediately after stretch, cells are harvested for protein. Western blotting analyses of the ratio of phosphorylated (p-) to total protein expression of (B) signal transducer and activator of transcription 3 (STAT3^Y705) (n = 9–12/group), (C) p38^T180/Y182 MAPK (n = 6/group), (D) extracellular signal-regulated kinase 1/2 (ERK1/2^T202/Y204) (n = 6/group), and (E) c-Jun N-terminal kinase (JNK^T183/Y185) (n = 9/group) protein expression. (F) Representative Western blotting images; dashed line represents different areas of the same gel. Data are presented as means ± SEM as a fold change from GM 0% stretch. Two-way ANOVAs were performed to determine differences. ^#Main effect of C26 + GM; *significant from GM 0% stretch, ^significant from C26 + GM 0% stretch. Statistical significance set at p ≤ 0.05.