Binds to FN14 and possibly also to TNRFSF12/APO3. Weak inducer of apoptosis in some cell types. Mediates NF-kappa-B activation. Promotes angiogenesis and the proliferation of endothelial cells. Also involved in induction of inflammatory cytokines. Promotes IL8 secretion (By similarity). Homotrimer. Interacts with the angiogenic factor AGGF1/VG5Q (By similarity). Widely expressed. The soluble form is produced from the membrane form by proteolytic processing. Belongs to the tumor necrosis factor family.