PIK3CA and cancer: Similar the EGFR-dependent activation of the Ras/Raf/mitogen-activated protein kinase-extracellular signal-regulated kinase-signaling pathway, and as shown for multiple other cancers, activation of the phosphatidylinositol-3-kinase (PI3K), protein kinase B (PKB/AKT), and mammalian target of rapamycin (mTOR) pathway is a frequent event in carcinogenesis that facilitates tumor formation, progression and therapy resistance (82–84).