Mustn1 silencing decreases myosin heavy chain (Myhc) expression during myogenic differentiation. The parental (A and B), control (C and D), and Mustn1 (E and F) RNAi-treated C2C12 cells were seeded on coverglasses and stained at day 2 (A, C, and E) and 4 (B, D, and F) with an anti-Myhc antibody. White arrows indicate multiple nuclei within individual myotubes. Scale bar, 50 μm.