MTOR and cancer: AMPK activation by metformin (up to10 mM for cells and 300 mg/kg for mice models) induces autophagy through inhibiting mTOR signaling or the immune response, and thus downregulates programmed death-ligand 1 (PD-L1) expression in a variety of cancer types, such as lymphoma, breast cancer, pancreatic cancer, non-small cell lung cancer, eventually, the growth or metastasis of cancer cells is inhibited [72–76].