Figure 4.
Effect of metformin on insulin-induced phosphorylation of Erk1/2 and S6K1 in cells treated or not treated with compound C, a specific AMPK inhibitor. T-I cells (2 × 106 cells/plate) were incubated without or with metformin (3mM) for 18 hours followed by compound C (20µM) or vehicle (dimethylsulfoxide) for 2 h and insulin (1µg/mL) or vehicle (acid water, pH 2) for 10 min. Cell lysates were analyzed for phospho-specific Erk1/2 (Thr202/Tyr204) in panel A and S6K (Thr389) in panel B and protein loading was normalized for Erk1/2 by Western blotting. Blots are representative of one experiment, and the graphs represent the mean of three experiments. Error bars represent mean ± SE. Each mean is labeled with a superscript (a or b). b, P < 0.05 vs other treatment groups (a).