And PD-L1 is also upregulated on tumor-associated MDSCs, which is regulated by the cyclooxygenase-2/microsomal PGE2 synthase 1/prostaglandin E2 (COX2/mPGES1/PGE2) pathway; the blockade of PD-L1 under hypoxic conditions enhances the activation of T cells by reducing IL-6 and IL-10 production from MDSCs [67,68]. This evidence concerns the gene PTGS2 and neoplasm.