MTOR and cancer: Many studies have suggested that the constitutive activation of Akt and consequently mTOR signaling is observed in many cancers; this AKT/mTOR signaling axis is central to the proliferation, invasion, angiogenesis, migration, and epithelial-to-mesenchymal transition (EMT) of cancer cells and is indispensable in the cellular mechanism of resistance to chemotherapy and radiotherapy [8,9,10,18,19,20,21,22], whereas little is known about the direct antitumor effect of rapamycin in OSCC cells.