In addition, some PTEN-deficient tumors are dependent on PI3Kβ signaling because depletion of PIK3CA has no impact on cell growth in three PTEN-deficient cancer cell lines, whereas inhibition of the PIK3CB isoform, responsible for encoding p110β, resulted in tumor growth suppression in vitro and in vivo (Wee et al., 2008). This evidence concerns the gene PTEN and cancer.