In addition to avoid from activating NK receptors, tumor cells can upregulate the expression of inhibitory ligands, such as HLA‐G (ligand for KIR), HLA‐E (ligand for NKG2A/CD94), or PD‐L1, which engage inhibitory receptors on NK cells, resulting in the inhibition of NK cell cytotoxicity.172. Here, HLA-E is linked to neoplasm.