PTGS2 and neoplasm: Tumor immunology studies showed that the COX-2/PGE2 pathway is exploited by tumors and myeloid derived suppressor cells (MDSCs) within the tumor microenvironment (TME) as a mechanism of immune evasion and a high expression level of Cox-2, associated with high level of PGE2 production, in these cells is correlated positively with their capacity of T cell suppression23, 33, 34.