KLRK1 and gastric cancer: In GC patients, the activating receptors NKG2D, NKp30, and NKp46 positive NK cells were also significantly down-regulated compared to the healthy controls (P < 0.001, P < 0.001, and P < 0.001, respectively); however, the inhibitory receptor KIR3DL1 positive NK cells was also significantly up-regulated compared to the healthy controls (P < 0.001).