KLRK1 and breast cancer: According to these data, spheroid-infiltrating NK cells showed an immunophenotype characterized by a state of activation and exhaustion with high expression levels of NKARs and inhibitory check-point molecules; moreover, similarly to NKp46 and NKG2D, (Fig. 5A), CTLA-4 expression on NK cells was differently influenced by the BC cell type (Fig. 5B).