Also, our results confirmed that exposing NK cells to ENT preserved cell viability and increased NKG2D levels, although we did not observe any increment in cytotoxicity as reported in previous studies using the same drug concentration but tumor targets other than K562 cells29,45; we speculate that the stimulating effect of ENT on NK cell cytotoxicity might depend on the nature of cell targets, eventually unveiled against cancer cells expressing very high levels of NKG2D ligands29,45. Here, KLRK1 is linked to cancer.