Metformin-mediated AMPK activation leads to an inhibition of mTOR signaling, a reduction in phosphorylation of its major downstream effectors, the eukaryotic initiation factor 4E-binding proteins (4E-BPs) and ribosomal protein S6 kinases (S6Ks), and an inhibition of global protein synthesis and proliferation in a number of different cancer cell lines [34,35,40,58]. This evidence concerns the gene MTOR and cancer.