PTEN and cancer: PTEN is one of the most frequently mutated tumor suppressors in human cancer and exerts its tumor suppressor activity via direct antagonism of the phosphatidylinositol 3-kinase (PI3K) signaling pathway by counteracting the PI(3,4,5)P3 production via PI3K (Chalhoub and Baker, 2009; Varga et al., 2009; Hollander et al., 2011).