Synonym APO-1, CD95 Fas, also known as APT1, tumor necrosis factor receptor superfamily member 6 (TNFRSF6), CD95, APO-1, and FAS1 is a type I membrane protein of about 40 kD. It was originally identified by mouse monoclonal antibody called anti-Fas or anti-APO-1. In the 6th Workshop and conference on Human Leukocyte Differentiation Antigens (Kobe, 1996), Fas was designated as CD95. The gene maps to 10q24 and is mutated in Autoimmune Lymphoproliferative Syndrome. The protein mediates apoptosis through sequential activation of ICE-like caspases (Casp 4, Casp 5, Casp 3) and may also be involved in autoimmune diabetes.