TNFRSF18, also known as tumor necrosis factor receptor superfamily member 18 isoform 1, is receptor for TNFSF18. It seems to be involved in interactions between activated T-lymphocytes and endothelial cells and in the regulation of T-cell receptor-mediated cell death. TNFRSF18 mediated NF-kappa-B activation via the TRAF2/NIK pathway. Also, this protein reciprocally stimulated and activate intracellular signals regulating immune functions. In particular, GITR-driven T-cell co-stimulation was found to be the main mechanism by which the GITRL-GITR system contributes to tumor rejection and the development of autoimmune/inflammatory diseases.