Hypoxia reportedly impair antitumor immune responses by activation of hypoxia-inducible factor-1α (HIF-1α) [93], which in turn, upregulates PD-L1 expression by MDSCs, macrophages, DCs, and tumor cells, thereby promoting T cell inactivation through the PD-1/PD-L1 axis [94, 95]. Here, CD274 is linked to neoplasm.