As aspirin irreversibly inhibits the activity of COX-2, a rate limiting enzyme in the synthesis of prostaglandin E2 (PGE2), and activation of PI3K-AKT pathway upregulates COX2 expression, it was hypothesized that constitutional activation of this signaling pathway by PIK3CA mutations might be predictive of aspirin’s benefits for CRC patients. The gene discussed is PTGS2; the disease is colorectal carcinoma.