KLRK1 and cancer: showed that incorporation of activating receptors such as natural killer group 2 member D (NKG2D) in the transmembrane region of CAR structure and 2B4 as a co-stimulating domain was able to enhance the cytotoxicity of CAR-NK cells, thus demonstrating the highest efficacy to eradicate cancer cells compared to other CAR structures which did not use NKG2D (82).