KLRK1 and neoplasm: Subsequently, our results showed that addition of anti-NKG2D antibody partially but significantly rescued CIK treatment-induced decrease in colony formation ability (Fig. 5B) and tumor sphere formation ability (Fig. 5C) of CIK-treated CNE2 and SUNE1 cells, suggesting that NKG2D blockade partially inhibited tumor-killing activity of CIK cells.