Cyclooxygenase-2 was first discovered as an oncogene-responsive isoenzyme, and increased COX-2 expression has been found in up to 85% of colorectal adenocarcinomas, while it is undetectable in normal intestinal mucosa (Giardiello et al, 1995; Kargman et al, 1995). The gene discussed is PTGS2; the disease is colorectal adenocarcinoma.