CD109, also named as CPAMD7, is a member of the alpha2-macroglobulin/complement superfamily. It is a glycosylphosphatidylinositol (GPI)-linked cell surface glycoprotein of approximately 170kd which is found on the cell surface of platelets, activated T-cells, and endothelial cells. CD109 binds to and negatively regulates signaling of transforming growth factor beta (TGF-beta). CD109 has been identified as part of the TGF-beta receptor system in human keratinocytes. Up regulation of CD109 expression has been observed in several different types of tumor.CD109 is a glycosyl-phosphatidylinositol-anchored glycoprotein that is a member of the a2-macroglobulin/C3, C4, C5 family of thioester-containing proteins. There're 2 forms of 150 (p150) and 120 kDa (p120) exist due to proteolytic degradation from a 180 kDa form. The antibody can recognize all these 4 isoforms.