Prostaglandin E2 (PGE2) can trigger mast cell activation, which can inhibit tumours by releasing IL-6 and TNF-α15 in a mechanism involving PTGER3, which plays an important role in suppression of cell growth, and its downregulation enhances colon carcinogenesis at a later stage and may oppose the pro-tumorigenic effects of PGE2 elevation and COX-2 overexpression in breast cancer16,17. This evidence concerns the gene PTGER3 and neoplasm.