Purity >98%. ZSTK474 is a triazine derivative that acts as an inhibitor of class I phosphatidylinositol 3-kinase (PI3K) isoforms (IC50 s = 17, 53, and 6 nM for p110Beta, -Gamma, and -Delta, respectively). It is selective for PI3K, as it has negligible activity against 139 other kinases when tested at 30 μM. ZSTK474 is orally bioavailable and shows strong antitumor activity against human cancer xenografts in mice. The efficacy of ZSTK474 against certain cancer cells and tumors can be enhanced by combination therapy.