mTORC1 activation is required for HepG2 cell survival, inhibited by berberine . HepG2 cells were either left untreated or treated with described concentration of berberine (10, 25, 50, 100 and 200 μM) for 4 hours, or treated with 100 μM of berberine for described time, expressions of phospho- and total Akt, S6 and 4EBP1, as well as Erk1/2 were tested by western blots (A and B). HepG2 cells were either left untreated or stimulated with RAD001 (200 nM) or rapamycin (200 nM), Akt and S6 activations were tested by western blots 4 hours after stimulation (C), cell viability was analyzed by MTT assay 48 hours after stimulation (D). HepG2 cells were pre-treated with the AMPK inhibitor compound C (AMPKi, 10 μM) for 1 hour, followed by berberine (100 μM) stimulation for 4 hours, expressions of S6 (p- and t-), p-4E-BP1 and Erk1/2 were tested by western blots (E). Experiments in this figure were repeated three times, and similar results were obtained. Data were expressed as mean ± SD. *p < 0.05 vs. Ctrl group (D).