KLRK1 and cancer: Several ligands for the activating immunoreceptor NKG2D (natural killer group 2D) (NKG2DL) including the UL16-binding protein (ULBP) family and MHC class I-related chain (MIC) proteins have been described to be selectively overexpressed in human cancer cells like acute myeloid leukemia, lung cancer, ovarian and breast cancer and sarcomas (15).