Fig. 1

Signaling pathways through which metformin acts in cancer. IGF-1 insulin-like growth factor-1, MAPK mitogen-activated protein kinase, REDD1 regulated in development and DNA damage 1, AMPK adenosine monophosphate-activated protein kinase, mTOR mammalian target of rapamycin, NF-κB nuclear factor kappaB, MDR1 multidrug resistance 1, HER2 human epidermal growth factor receptor-2, IGF-1R IGF-1 receptor, IR insulin receptor