Figure 3

Growth factors, but not amino acids, promote the degradation of PDCD4. L6 myotubes were incubated in differentiation (Ctl) or starvation medium as described in Figure 1. They were then harvested (Stv) or refed in the differentiation medium (DM), serum-free AMEM (AMEM), or in starvation medium supplemented with either 0.4 mM leucine (LEU), 10% dialyzed FBS (FBS) or 2% horse serum (HS) for 1 h. (A) Cells were harvested and analyzed by immunoblotting. (B) PDCD4 signals were quantified and expressed relative to γ-tubulin. Means ± SE; n = 4; bars with different letters differ (P < 0.05).