TRAFs are a family of intracellular adaptor proteins that interact with a wide range of cell surface receptors and participate in the regulation of cell survival, proliferation, differentiation, and stress responses. TRAFs were identified by their ability to form complexes with TNF receptor superfamily members, although they also associate with Toll/IL-1 receptor family members as well. They mediate the interaction between receptors and a range of molecules including other adaptor proteins and kinases. At least six members of the TRAF family have been identified (TRAF-1 through -6). All TRAF proteins have a homologous C-terminal TRAF domain that can bind the cytoplasmic domain of receptors as well as other TRAFs.