Gain-of-function mutations of RAS, BRAF, PIK3CA genes, or loss of tumor suppressor function of PTEN, resulting in continuous activation of the RAS-mitogen-activated protein kinase (MAPK) or phosphoinositide 3-kinase (PI3K) pathways, characterize most colorectal cancers (CRC) [7-9]. The gene discussed is PIK3CA; the disease is colorectal cancer.