Indeed, NK cell-mediated anti-tumor responses are also governed by other inhibitory receptors expressed on different immune cells including NK cells, such as T-cell Ig and mucin-containing domain-3 (Tim-3) [18], Lymphocyte Activation Gene 3 (LAG-3) [19] and PD-1 [20] whose ligands are non-MHC class I related molecules (Figure 1). The gene discussed is PDCD1; the disease is neoplasm.