Natural cytotoxicity triggering receptor 2 (NCR2), also known as Natural killer cell p44-related protein (NKp44), or CD336, is a member of the natural cytotoxicity receptor (NCR) family, which composed of one Ig-like extracellular domain, a transmembrane segment, and a cytoplasmic domain. It is a novel transmembrane glycoprotein belonging to the Immunoglobulin superfamily characterized by a single extracellular V-type domain. The cytoplasmic domain of NKp44 also contains a sequence that matches the immunoreceptor tyrosine-based inhibitory motif (ITIM) consensus. This Cytotoxicity-activating receptor may contribute to the increased efficiency of activated natural killer (NK) cells to mediate tumor cell lysis. NKp44 is selectively expressed by IL-2-activated NK cells and may contribute to the increased efficiency of activated NK cells to mediate tumor cell lysis. Tumor cell recognition of the mutated NKp44 proteins was significantly reduced and correlated with their lower recognition of heparin.