Tumor necrosis factor (beta) (TNF(beta)), also known as lymphotoxin, is a pleiotropic cytokine. TNF(alpha), also known as cachetin, is a cytokine that binds to the same receptors, producing an array of effects similar to those of TNF(beta). TNF(beta) and TNF(alpha) share 30% amino acid homology and have similar biological activities. TNF(beta) is produced by activated lymphocytes, including CD4+ T helper cell type 1 lymphocytes, CD8+ lymphocytes and certain B lymphoblastoid cell lines. TNF(alpha) is produced by several different cell types, including lymphocytes, neutrophils and macrophages. TNF(beta) and TNF(alpha) can modulate many immune and inflammatory functions while having the ability to inhibit tumor growth. TACE (for TNF(alpha) converting enzyme) is a metalloproteinase that cleaves the membrane-bound TNF(alpha) precursor to release soluble TNF(alpha).