MICA and cancer: Hypoxia contributes to immune evasion through various mechanism (63), including promoting the shedding of the major histocompatibility complex (MHC) class I polypeptide-related sequence A (MICA) (22, 64), as well as inducing the expression of checkpoint inhibitor, PD-L1, by cancer cells (65, 66), and myeloid derived suppressor cells (MDSCs) (66).