Knockdown of Set7 impairs skeletal muscle myocyte differentiation. (A) C2C12 myoblasts were transfected with control siRNA or siRNA against Set7 together with a GFP expression construct. Cells were transferred to differentiation medium for 72 h, and myoblast differentiation was observed under a fluorescent microscope. Bar, 40 µm. (B) The quantitative analysis result of the mean myotube numbers from 10 randomly chosen microscopic fields. Data represent the means ± SD from at least three independent experiments. si, siRNA. ***, P < 0.001. (C) C2C12 myoblasts were transfected with control siRNA or siRNA against Set7. Cells were transferred to differentiation medium for the indicated time, and Western blot analyses were performed using antibodies that recognize the indicated proteins. β-Tubulin was used as a loading control. Phos H3, phospho–histone H3; MHC, myosin heavy chain; Crtl., control. Black lines indicate that intervening lanes have been spliced out.