GYPA (Glycophorin A) is a sialoglycoprotein found on erythrocyte membranes that bears the antigenic determinants for the MNS blood group system. GYPA is also a receptor for a number of viruses such as hepatitis A and influenza and is a target of invasion by the parasite Plasmodium falciparum. In immunohistochemistry, it has membranous staining in erythroblasts and erythroid cells. In cancer, it is used to identify the M6 subtype of acute myeloblastic leukemia and it is also positive in erythroleukemia. References: Hum Genet. 2018 Feb; 137(2):151-160, PMID: 29362874; Biochem. J. 1983 Jan. 209 (1): 273–6. doi:10.1042/bj2090273, PMID: 6342608; Journal of Human Genetics. 2007 Mar. Volume 52, pages 476–479, DOI: 10.1007/s10038-007-0133-6