PTGS2 and ileus: COX-2 catalyzes the first step of conversion of its common substrate, arachidonic acid (AA), into a number of biologically active derivatives, designated as prostaglandins (PGs, including PG-E2, PG-D2, PGF-2α, and PG-I2) and thromboxane (TX) A2, which are major participants in rodent postoperative ileus [8].