Figure 3

Downregulation of cyclin D1 corresponds to activation of AMP-activated protein kinase. A. MCF7 cells were treated with (Met) or without (Con) metformin for 1.5 days and then western blotting was performed to detect active phospho-AMPK, cyclin D1, and β-actin. B. MCF7 cells were treated with antimycin A (AM, 1 μM), AICAR (4 mM), or metformin (8 mM) for 1.5 days. Control cells (Con) were treated with the appropriate vehicle for each reagent. Western blotting was performed to detect active phospho-AMPK, cyclin D1, and β-actin. C. MCF7 cells were pretreated with DMSO (vehicle) or the AMPK-specific inhibitor compound C (20 μM) for 1 day and then treated with (Met) or without (Con) metformin for 1.5 days. Western blotting was performed to detect cyclin D1 or the phosphorylated form of the AMPK substrate ACC. β-actin was used as a loading control.