PTEN and neoplasm: We also examined a second mouse tumor model, Pten+/−, for interaction with Mtap. Pten (Phosphatase and Tensin Homolog) is a phosphatase that dephosphorylates phosphatidylinositol (3,4,5)-trisphosphate resulting in the formation of phosphatidylinositol (4,5)-biphosphate, which causes inhibition of the AKT signaling pathway.