Fas-associating death domain containing protein (FADD), also known as mediator of receptor induced toxicity (MORT1), is a 23 kDa cytosolic protein with an apparent molecular weight of 28 kDa on SDS-PAGE. The protein is involved in both Fas and TNF-R induced cell death pathway. FADD specifically binds to Fas to initiate the apoptotic signalling cascade. Overexpression of FADD induces apoptosis.