ABIN-3 is a member of the A20-binding inhibitor of NF-kappaB activation (ABIN) protein family. Similar to the previously characterized human ABINs (ABIN-1 and ABIN-2), ABIN-3 can bind to A20 and inhibit NF-kappaB activation. In contrast, mouse ABIN-3 is incapable of inhibiting NF-kappaB activation by proinflammatory stimuli because the protein lacks a complete ABIN homology domain, which is required for the funcitonal activity of human ABIN-3.