CD300a is an inhibitory receptor that is involved in downregulating cytolytic activity in natural killer (NK) cells as well as negatively regulating mast cell degranulation. CD300 is found on leukocytes and functions in immune response signaling pathways. CD300A plays a role in tumorigenesis in various tissues; it has been found to promote progression in acute myeloid leukemia and diffuse large B-cell lymphoma, where it serves as a marker of poor prognosis and is a potential therapeutic target. In immunohistochemistry of normal tissue, CD300A has high membranous and cytoplasmic positivity in immune cells and is expressed in all tissues throughout the body. References: The UniProt Consortium. Nucleic Acids Res. 47: D506-515 (2019); Nucleic Acids Res. 2016 Jan 4;44(D1):D733-45, PMID:26553804; Oncotarget. 2015 Oct 13; 6(31): 31191–31202, PMID: 26435477; Oncotarget. 2018 Jun 8; 9(44): 27574–27584, PMID: 29938007;