In addition, the percentage of perforin expression NK cells in GC patients was also significantly decreased, and its level positively correlated with the proportion of NKp30, NKp46, NKG2D, and DNAM-1 expressing NK cells (Supplementary Figure 3), suggesting that NK cell functional impairment is linked to their decreased expression of activating receptors. This evidence concerns the gene KLRK1 and gastric cancer.