Killer cell lectin-like receptor subfamily B member 1, also known as KLRB1, plays an inhibitory role on natural killer (NK) cells cytotoxicity. Natural killer (NK) cells are lymphocytes that mediate cytotoxicity and secrete cytokines after immune stimulation. Several genes of the C-type lectin superfamily, including the rodent NKRP1 family of glycoproteins, are expressed by NK cells and may be involved in the regulation of NK cell function.