KLRK1 and hepatocellular carcinoma: However, the blocking of IL-6 in their supernatants significantly enhanced the expression of NK activating receptors NKG2D and NKG2C on the surface of NK-92 cells on HIF-1α-expressed HCC SK-Hep1 cells (Fig. 3, NKG2D+; CoCl2 18.38%, CoCl2 + Anti-IL-6 25.86%, NKG2C+; CoCl2 2.90%, CoCl2 + Anti-IL-6 6.28%, **p < 0.05).