Potent mTOR inhibitor (IC50 = 15 nM). Exhibits >60-fold selectivity for mTOR over PI 3-kinases and is inactive against a panel of other kinases. Inhibits growth of ER-positive MCF7 breast cancer cells in vitro (EC50 = 8.5 nM). Cell permeable. Purity 98%. MW (observed): 383.41