PIK3CD and cancer: Indeed, recent studies have shown that there is poor correlation between the PIK3CA or PTEN mutational status in cancer cell lines and the response of these cells to anti-proliferative effect of PI3K inhibitors (Edgar et al., 2010; O'Brien et al., 2010; Tanaka et al., 2011) indicating that unidentified mechanisms or PI3K isoform(s) other than p110α are also involved in the control of cancer cells survival.