– Mouse Apoptosis-mediating surface antigen FAS (Fas) belongs to the death receptor subfamily of the TNF receptor superfamily and is designated TNFRSF6. Mouse Fas contains 1 death domain and 3 TNFR-Cys repeats. It detected in various tissues including thymus, liver, lung, heart, and adult ovary. As a receptor for TNFSF6/FASLG, The adapter molecule FADD recruits caspase-8 to the activated receptor. The resulting death-inducing signaling complex (DISC) performs caspase-8 proteolytic activation which initiates the subsequent cascade of caspases mediating apoptosis. FAS-mediated apoptosis may have a role in the induction of peripheral tolerance, in the antigen-stimulated suicide of mature T-cells, or both.