BAFF (B cell-activating factor belonging to the TNF family) is a membrane protein expressed by dendritic cells, monocytes, macrophages, follicular dendritic cells, activated T cells, activated neutrophils, and malignant B cells. BAFF, also known as BLyS (B lymphocyte stimulator), is a potent B cell growth factor. Proteolytic cleavage can result in the release of a soluble trimeric BAFF which binds to the BAFF receptor, BCMA and TACI. The release of soluble BAFF is regulated by IFN-? and to a lesser extent IL-10. BAFF protects B cells from apoptosis and increases the expression of anti-apoptotic proteins Bcl-2 and Bcl-xL.Synonyms: B cell-activating factor, B lymphocyte stimulator, BAFF, BLYS, Dendritic cell-derived TNF-like molecule, TALL1, TNF- and APOL-related leukocyte expressed ligand 1, TNFSF13B, TNFSF20, Tumor necrosis factor ligand superfamily member 13B, ZTNF4