PTEN and neoplasm: While it is clear that PTEN asserts its tumour suppressive role via the hydrolysis of PtdIns(3,4,5)P3 and PtdIns(3,4)P2, thereby controlling AKT phosphorylation, the 5-phosphatases play a more diverse modulatory role in regulating multiple phosphoinositide species, and AKT activation.