PP242 is an ATP-competitive, pyrazolopyrimidine-based inhibitor of mTOR at an IC50 of 8 nM. It is highly selective against the PI3K family of kinases, with all but one isoform (p110g IC50 = 102 nM) registering with IC50s > 1 uM. In a broad kinase panel, PP242 showed modest activity only in PKCa and JAK2 at IC50s of 49 and 110 nM, respectively. [1] PP242 inhibits insulin-stimulated phosphorylation of Akt at S473, as well as phosphorylation at T308.

PP242 inhibits TORC1 and TORC2 function and inhibits phosphorylation (S473) in studies where Rapamycin has been shown to be less effective. Moreover, phosphorylation studies on S2481, a marker for TORC2 activity, showed that PP242 inhibition was significant, whereas rapamycin had little effect. [2] Cell-cycle analysis showed that PP242 induced both arrest and apoptosis, whereas rapamycin was cytostatic. [3]