PTGS2 and neoplasm: The presence of anti-inflammatory soluble factors released by tumour-associated corrupted cells, such as IL-10, transforming-growth-factor-β (TGFβ), cyclooxygenase-2 (COX2), inducible nitric oxide synthase (iNOS) and PGE2, induces the expression of several negative ligands (FasL, PDL1, PDL2, Galactin 9, ect).