PTGS2 and neoplasm: In mouse bladder cancers, PD-L1 expression on tumor-associated myeloid cells is associated with the expression of cyclooxygenase-2 (COX2), microsomal prostaglandin E synthase-1 (mPGES1), prostaglandin E2 (PGE2) and the capacity to induce apoptosis of CD8+ T cells (51).