ZUP1 and ovarian neoplasm: The molecular mechanism responsible for the NF-κB inhibitory function of A20 has been clarified by the elucidation of A20 as an ubiquitin-editing protein with dual functions: a deubiquitinating enzyme (DUB) activity mediated by its N-terminal ovarian tumor (OTU) domain and E3 ubiquitin ligase activity mediated by the C-terminal zinc finger containing domain [21].