MTOR and colorectal cancer: In accordance with the notion that Akt-mTOR signaling is a negative regulator of autophagy [35], gambogic acid, isolated from gamboge resin, can enhance the ROS accumulation and suppress phosphorylation of both Akt (S473) and mTOR (S2448) to induce autophagy in colorectal cancer HCT116 cells [36].