Human peripheral blood lymphocytes are stained with PE Anti-Human CD9 Antibody (filled gray histogram). Unstained lymphocytes (empty black histogram) are used as control.
CD9 is a 24 kD type III transmembrane protein also known as tetraspanin, MRP-1 and DRAP-24. It is a member of the tetraspan family (spanning the membrane four times) found on platelets, B cell progenitors, activated lymphocytes, granulocytes, endothelial cells and epithelial cells. CD9 induces adhesion, platelet aggregation, and B cell development. CD9 has been shown to associate with CD63, CD81, CD82, and CD36 and to bind to β1 integrins.