Tumor necrosis factor ligand superfamily member 4 (TNFSF4) is also known as glycoprotein Gp34, OX40 ligand (OX40L), TAX transcriptionally-activated glycoprotein 1 and CD252, which belongs to the tumor necrosis factor family. TNFSF4 is the ligand for CD134 and is expressed on such cells as DC2s (a subtype of dendritic cells) enabling amplification of Th2 cell differentiation. The interaction of TNFSF4-TNFSF4 is involved in the pathogenesis of multiple autoimmune and inflammatory diseases such as systemic lupus erythematosus (SLE), carotid artery disease and cancer. Furthermore, similar to other TNF superfamily members, membrane-bound OX40 Ligand (TNFSF4) exists as a homotrimer. Human TNFSF4 shares 46% amino acid sequence identity with its mouse counterpart.