KLRK1 and neoplasm: Flow cytometry showed that, in tumor, the frequency of activating receptor NKG2D+ NK cells and the expression level of DX5 on NK cells in HSCT recipients were similar to those in the no‐treatment group (Fig. 2A), whereas the frequency of inhibitory receptor NKG2A+ NK cells was markedly decreased in the tumor but not in the spleen of HSCT recipients (Fig. 2B).