PDCD1 and neoplasm: In order to survive and evade the immune response, highly mutated tumor cells use several evasion techniques including downregulating MHC I expression, though natural killer cells are more likely to target these without the involvement of a separate evasion mechanism involving shedding like in some prostate cancers [4], since the presence of MHC I inhibits their activity [2, 5], and expressing immune checkpoint surface proteins, such as programmed cell death 1 (PD‐1) ligands [6] to dull the adaptive response their foreign antigens trigger.