PI3Ks are a family of related intracellular signal transducer enzymes capable of phosphorylating the 3 position hydroxyl group of the inositol ring of phosphatidylinositol (PtdIns).[2] The pathway, with oncogene PIK3CA and tumor suppressor PTEN, is implicated in the sensitivity of cancer tumors to insulin and IGF1, and in calorie restriction.[3][4]