PTGS2 and neoplasm: Consistently, another recent study has demonstrated that tumor-derived TGF-β induces CD39/CD73 expression on MDSCs from lung cancer patients through the mammalian target of rapamycin (mTOR)-hypoxia-inducible factor 1α (HIF-1α) pathway, and these CD39+CD73+ MDSCs represent a distinct subpopulation that expresses higher levels of HIF-1α, cyclooxygenase 2 (COX2), IL-10, tumor necrosis factor (TNF)-α, and TGF-β as compared to their counterparts (32).