PTGS2 and neoplasm: COX2 is the rate-limiting enzyme of prostaglandin synthesis, and it is also highly expressed in inflammation, tumor, and other pathological states.329 Hsu et al.330 found that knocking out the mouse TLR4 gene significantly reduced the expression of COX2 and PGE2 in the intestinal mucosa; after administration of PGE2, the expression of COX2 in the intestinal mucosa increased significantly and promoted the occurrence of intestinal tumors.