PIK3CA and neoplasm: In colon cancer, an abnormally activated PI3K/Akt pathway can inhibit p53-independent apoptosis by phosphorylating mTOR and its downstream regulators p70S6K, 4EBP1, etc. (105); this pathway can also involve in regulating VEGR expression in tumor angiogenesis (106) and the expression of cyclinD1 and p21 (107).