PIK3CA and cancer: The PI3K/Akt/mTOR signaling pathway has been described as one of the most activated pathways in various types of cancer [75], as a result of mutations in the phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit alpha (PIK3CA) or by the loss of phosphatidylinositol-3,4,5-trisphosphate 3-phosphatase (PTEN).