FIGURE 2.

shRNA-mediated knockdown of MEF2 proteins in C2C12 myoblasts. C2C12 myoblasts were transduced with adenoviruses harboring shRNAs targeting Mef2a, -b, -c, or -d, or with an shRNA against lacZ as a negative control. A–C, knockdown of Mef2a (A), but not Mef2b, -c, or -d, resulted in impaired myotube formation and differentiation as shown by Western blot analysis of the muscle-specific marker myosin heavy chain (MHC) (B and C). D, combinatorial knockdown of Mef2a/b, Mef2a/c, and Mef2a/d failed to modulate the differentiation defect observed in the Mef2a knockdown alone. Additionally, simultaneous knockdown of Mef2b/c, Mef2b/d, Mef2c/d, and Mef2b/c/d failed to produce any overt morphological defects in C2C12 differentiation. E and F, Western blot analysis of myosin heavy chain (E) and accompanying densitometry (F) for the combinatorial knockdowns show that differentiation is only affected in MEF2A depleted cells. The data are means ± S.E. **, p < 0.01; ***, p < 0.001.