In colorectal cancer (CRC), mutations of EGFR downstream targets occur especially in the GTPase KRAS in up to 45% and in the phosphatidylinositol-4,5-bisphosphate 3-kinase, catalytic subunit alpha (PIK3CA) in up to 30% of patients [4,6–8]. The gene discussed is PIK3CA; the disease is colorectal carcinoma.