Figure 5. The increase of Akt phosphorylation by silibinin in insulin-resistant C2C12 myotubes was suppressed by 50 nM wortmannin, a specific inhibitor of phosphatidylinositol-3-kinase (PI3K). Differentiated C2C12 skeletal muscle cells were incubated with palmitate (0.75 mM) and/or silibinin (100 μg/mL) in the presence or absence of wortmannin (50 nM), and then stimulated with insulin (100 nM) before cells were harvested for Western blotting. Figures are representative of 3 independent experiments.