The biologic activity of metformin is dependent upon the integrity of the AMPK/TSC2/mTOR axis. (A) Western blot analysis of the phosphorylation levels of AMPK_α T¹⁷², ACC S⁷⁹, and 4E-BP1 S⁶⁵ in the MV4-11 leukemic cell line treated without or with 20 μM compound C for 30 minutes, then without or with 10mM metformin for 2 additional hours. (B) Western blot analysis of the phosphorylation levels of AMPK_α T¹⁷², ACC S⁷⁹, and 4E-BP1 S⁶⁵ in TSC2 knock-down MV4-11 cells cultured for 24 hours without or with 10mM metformin. (C) Western blot analysis of the phosphorylation levels of P70S6K T³⁸⁹, and 4E-BP1 S⁶⁵ in HEK293 cells transfected with mTOR^WT or mTOR^SL1+IT plasmids and then treated or not with 10mM metformin.