CD95 is a 45 kD single chain type I glycoprotein also known as Fas, APO-1, and TNFRSF6. It is a member of the TNF receptor superfamily. CD95 is expressed on T and B lymphocytes, monocytes, neutrophils and fibroblasts. CD95 expression is upregulated by activation. The extracellular region of CD95 binds to CD178 (Fas ligand). CD178 binding to CD95 induces apoptosis, and has been shown to play a role in the maintenance of peripheral tolerance. The EOS9.1 antibody is useful for inducing apoptosis of Fas-positive cells.