Background：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.
