ROS are essential in tetrandrine-induced autophagy. (A) Intracellular ROS accumulation levels measured by flow cytometry after tetradrine treatment for the indicated times in Hela and MCF-7 cells. (B) Hela and MCF-7 cells were pretreated with 15 mM NAC for 1 hour and then with tetrandrine for 24 hours. Intracellular ROS levels were measured by flow cytometry. Autophagy detected by western blot analysis of LC3 levels (C) and GFP-LC3 dots accumulation assay (D) in cells pretreated with NAC, ** p < 0.01.