The clinical significance of RPTOR is primarily due to its involvement in the mTOR pathway, which plays roles in mRNA translation, autophagy, and cell growth. Mutations in the PTEN tumor suppressor gene are the best known genetic deficiencies in cancer which affect mTOR signaling. These mutations are frequently found in a very large variety of cancers, including prostate, breast, lung, bladder, melanoma, endometrial, thyroid, brain, and renal carcinomas. PTEN inhibits the lipid-kinase activity of class I PtdIns3Ks, which phosphorylate PtdIns(4,5)P to create PtdIns(3,4,5)P (PIP3). PIP3 is a membrane-docking site for AKT and PDK1. In turn, active PDK1, along with mTORC1, phosphorylates S6K in the part of the mTOR pathway which promotes protein synthesis and cell growth.
