VSIR and neoplasm: Hypoxia also promotes the immunosuppressive function of MDSC by upregulating the VISTA expression (29), induces tumor cell escape from phagocytosis by upregulating the CD47 (30), and stimulates the expression of the Non-Classical MHC class I (HLA-G) to inhibit the function of several immune cells, including B cells, T cells, natural killer cells, and dendritic cells (31, 32).