PTGS2 and urinary bladder cancer: In mouse bladder cancers, PD-L1 expression on tumor-associated MDSCs was associated with the expression of cyclooxygenase-2 (COX2), microsomal prostaglandin E (mPGES1), and prostaglandin E2 (PGE2), as well as their capacity to induce apoptosis of CD8+ T cells (78).