MTOR and neoplasm: Moderate-dose ROS like O2•- and H2O2 facilitate the abnormal proliferation, metastasis, and infiltration of various tumor cells through activating multiple pathways including oxidative stress-related pathways and antioxidant stress pathways, such as the mitogen activated-protein kinase (MAPK) pathway, the phosphoinositide-3-kinase (PI3K)/protein kinase B (PKB or AKT)/mammalian target of rapamycin (mTOR) pathway, the nuclear factor-κB (NF-κB) pathway, and the nuclear factor erythroid 2-related factor 2 (Nrf2) pathway [38].