Fig. 6.

ERK1/2 and p38 MAPK signaling in metformin-mediated CAR phosphorylation. Human hepatocytes (HL#77, #78, and #80) were treated with MET (1 mM) for 0, 15 minutes, and 1, 4, and 24 hours. Homogenate proteins from each treatment group were used for Western blot analysis of AMPK (Thr172), ERK1/2 (Thr202/Tyr204), p38 MAPK (Thr180/Tyr182), and β-actin (A). Real-time PCR was employed to measure CYP2B6 expression in human hepatocytes (HL#74 and #80) treated for 24 hours with 0.1% DMSO, MET (0.1, 0.5, 1 mM), U0126 (10 µM), PB (1 mM), CITCO (1 µM), SB212190 (1, 5, 10 µM), or their different combinations as indicated in B and C. Dephosphorylation of ERK1/2 by U0126 (10 µM) and p38 MAPK by SB212190 (10 µM) were analyzed in treated hepatocytes (HL#82). Data represent the mean ± S.D. of three independent transfections (*P < 0.05; **P < 0.01).