KLRK1 and breast cancer: Currently, several CAR-NK constructs recognizing EGFR in breast cancer with metastases to the brain [190], ErbB2/HER2 in breast cancer [191,192], EGFRvIII in glioblastoma [193], GD2 in neuroblastoma [194], EpCAM in breast carcinoma [195], NKG2D in ovarian cancer [196], and MUC1 and ROBO1 in various refractory solid tumors have been developed and are already used for both preclinical studies and phase I/II clinical trials (Table 1).