TNFRSF19 is a novel member of the tumor necrosis factor receptor superfamily. also known as TRADE, TROY and TAJ. The extracellular domain of this type I transmembrane protein contains two complete and one partial match to the conserved cysteine-rich domains that characterize this family of receptors. The tnfrsfl9 gene maps to chromosome 14 and in situ hybridization reveals that it is expressed in a range of embryonic tissues, especially in the developing nervous system and pulmonary epithelium. In the adult mouse. TNFRSF19 expression is detected in the pulmonary epithelium and the ductal epithelium of the prostate and parotid glands. Iminunohistochemical analysis has demonstrated localization of human TNFRSF19 to ductal epithelial cells in the prostate and parotid glands. Correspondingly. TNFRSF19 expression is detected in some adenocarcinoma cell lines that arise from this tissue. TNFRSF19 signals activation of the Jnk pathway and induces cell death. Overexpression of TNFRSF19 also signals NFaB activation, comparable and similar to that by р75NGFR. TNFRSF19 is capable of activating key signaling pathways of the TNF receptor family, and its predominant expression patterns suggest that it plays a role in the growth and regulation of epithelial tissues. The ligand(s) for this receptor remain to be identified.