MTOR and cancer: The PI3K (phosphatidylinositol-4,5-bisphosphate 3-kinase)-Akt (protein kinase B)-mTOR (mammalian target of rapamycin) signaling pathway is a signal transduction pathway involved in the regulation of multiple cellular functions including cell proliferation, survival, differentiation, adhesion, motility, and invasion, which is one of the most frequently dysregulated pathways in human cancers [16].