MTOR and neoplasm: Our current understanding of the mechanism by which metformin inhibits tumor cell invasion, migration, and proliferation can be roughly divided into the following pathways [9–15]: (1) Metformin inhibits the downstream mTOR pathway by activating the AMP-activated protein kinase (AMPK) signaling pathway to inhibit tumors; (2) Metformin inhibits tumors by activating reactive oxygen species (ROS) and the C-Jun N-Terminal Kinase 1 (JNK) signaling cascade; (3) Metformin can enhance the cytotoxicity of chemotherapy drugs.