PTEN (Phosphatase and tensin homolog) is a protein that, in humans, is encoded by the PTEN gene.[4] Mutations of this gene are a step in the development of many cancers. 
 It negatively regulates intracellular levels of phosphatidylinositol-3,4,5-trisphosphate in cells and functions as a tumor suppressor by negatively regulating Akt/PKB signaling pathway.