TWEAKR belongs to the TNF family of transmembrane proteins, and contains a cytoplasmic “death domain”, which can activate a cell’s apoptotic machinery. It is expressed in the spleen, thymus, peripheral blood lymphocytes, colon, and small intestine. Signal transduction by TWEAKR can be activated by either membrane-anchored or soluble TWEAK. Recombinant Human soluble TWEAKR is a 53 amino acid polypeptide (5.6 kDa) comprising the entire extracellular domain of the full-length TWEAKR protein.