The TNFR family, or tumor necrosis factor superfamily (TNFRSF), is a broad group of related cytokine receptors responsible for initiating signaling for apoptosis, inflammation, proliferation, survival and differentiation. Members of this family are characterized by transmembrane domains and cysteine-rich domains that form scaffolds of disulfide bridges. Upon ligand binding, TNF receptors trigger intracellular signal transduction by binding adaptor proteins in a 3:3 complex. Some notable members of this 27-member family include TNFR1, TNFR2, FAS/CD95, TWEAK receptor/Fn14, and the TRAIL receptors (DR3, DR5). ELISA kits for the detection of TNF receptors are available from a variety of manufacturers, prepackaged and ready to use.