Members in the TNF and its receptor superfamilies regulate immune responses and induce apoptosis. DR3 (also termed Wsl-1, Apo-3, TRAMP, and LARD) is preferentially expressed by T lymphocytes and upregulated during T cell activation. The ligand for DR3 was recently identified and designated TL1A. TL1A also binds decoy receptor DcR3/TR6, which is expressed in several lung and colon carcinomas and in some normal tissues. TL1A induces apoptosis and NF-κB activation in DR3 expressing cells, which is antagonized by DcR3. TL1A is upregulated by proinflammatory cytokines TNF and IL-1. TL1A is a longer variant of TL1 (also called VEGI).