EBS-CD-12 recognizes an extracellular epitope on an integral membrane glycoprotein of 150 kDa, identified as CD13 (also known as aminopeptidase-N). CD13 is present on most cells of myeloid origin including granulocytes, monocytes, mast cells, and GM-progenitor cells. It is also expressed by the majority of AML, CML in myeloid blast crisis, and in a smaller fraction of lymphoid leukemias. CD13 is also present on fibroblasts; endothelial cells, epithelial cells from renal proximal tubules and intestinal brush border, bone marrow stromal cells, osteoclasts, and cells lining bile duct canaliculi. CD13 plays a role in metabolism of biologically active peptides, in phagocytosis, and in bactericidal/tumoricidal activities. It also serves as a receptor for human coronaviruses (hCoV) and human cytomegalovirus (hCMV). Positive control: Human lymph node, tonsil or brain.