Considering the complex regulation of NK cell responses, we will focus only on selected inhibitory receptors that are known to suppress NK cells functions in tumour, such as KIR2DL1–3, KIR3DL1–2, NKG2A/CD94, TIGIT, PD-1, LAG-3, and Tim-3 (Figure 1) [37,38,39,40,41]. This evidence concerns the gene PDCD1 and neoplasm.