Selective inhibitor of mammalian target of rapamycin (mTOR) (IC50 ~10 nM for mTORC1 and mTORC2 respectively). Displays no activity at PI 3-kinase or 76 other kinases tested. Inhibits activation and hydrophobic motif phosphorylation of Akt, S6K and SGK, but not RSK. Suppresses cell growth and induces G1 cell cycle arrest in vitro.