Figure 1: Modification of proTNF-α by TACE/ADAM-17. TNF-α is expressed as a monomeric precursor TNF-α which assembles as trimer at the membrane, forming proTNF-α. The extracellular 17 kDa domain of each proTNF-α subunit is enzymatically cleaved by TACE/ADAM-17 to form the soluble form of TNF-α, sTNF-α, the biologically active form of TNF-α.