Figure 5.

E2F1 stability during myogenic differentiation. C2/C12 cells were grown as undifferentiated myoblasts in growth medium (GM) or, for 48 hr, in differentiation medium (DM). (Left) E2F1 Northern blot using equivalent amounts of total RNA derived from C2/C12 myoblasts and myotubes. RNA from E2F1−/− murine embryonic fibroblasts served as a negative control. (Right) E2F1 and pRb Western blots of identical quantities of cell extract protein derived from C2/C12 myoblasts (GM) and myotubes (DM), respectively. The arrows indicate differentially phosphorylated E2F species.