PIK3CA and cancer: The PI3Ka/mammalian target of rapamycin (mTOR) pathway is frequently dysregulated in cancer because of mutation, amplification, or both, of the genes such as those encoding the PI3K catalytic subunits p110a (PIK3CA) and p110b (PIK3CB), the PI3K regulatory subunit p85a (PIK3R1), AKT1-3, and the phosphatidylinositol-3,4,5 trisphosphate (PIP3) phosphatases PTEN and INPP4B [7,8].