A20 is a deubiquinating enzyme acting as a negative regulator in the nuclear factor κB (NF-κB) pathway.1 It is encoded by the tumor necrosis factor (TNF)-alpha induced protein 3 (TNFAIP3) gene and consists of 2 domains: an amino-terminal ovarian tumor domain carrying the deubiquitinating activity, and a carboxy-terminal zinc finger domain, which has ubiquitin ligase and polyubiquitin-binding ability.1
