A potent and selective in vitro mTOR inhibitor that targets the ATP domain of mTOR (IC₅₀ = 8 nM). Inhibits other PI 3-Kinases only at much higher concentrations. Recently it has been shown that PP242 is a more effective mTORC1 inhibitor than Rapamycin (Cat. No. 1568-5 & 1568-50).