EPAS1 and cancer: For instance, PD-L1 is secreted by hypoxia-induced HIF-1α, but not HIF-2α in MDSCs,330 arginase and NO are promoted by HIF-1α-induced miR-210 expression,331,332 surface ectonucleotidases CD39 and CD73,333 TGF-β1, and exosomes, such as S100A9, RAR-related orphan receptor alpha (RORA), and PTEN,281,334,335 promote cancer cell stemness and growth and inhibit CTL function.