CD13/aminopeptidaseNis a150 kDacellsurfaceglycoprotein,which wasoriginally usedas amarkerforsubpopulationsofhematopoieticcells. CD13 iswidelydistributed in a variety of mammalian cells,such as monocyte/macrophages,fibroblasts,neutrophils,endothelial cells,and epithelial cells. CD13 is also a pan-myeloid marker,present on mature granulocytes and monocytes.