CD43,also named leukosialin,sialophorin,galactoglycoprotein,leukocyte sialoglycoprotein,SPN,and is a mucin-like type I transmembrane protein. In humans,it is expressed in haematopoietic cells,including T lymphocytes,monocytes,granulocytes,natural killer cells,platelets,and haematopoietic stem cells,with the exception of mature erythrocytes and B cell subpopulations. The unglycosylated form of CD43 migrates on SDS-PAGE with a molecular weight of 54 kDa ,whereas CD43 from different haematopoietic cell lines displays increased molecular weights since it is glycosylated with O-linked chains that differ in core structure and sialylation.