UniProt Summary: Cleaves 'Lys-63'-linked poly-ubiquitin chains, and with lesser efficiency 'Lys-48'-linked poly-ubiquitin chains (in vitro). May act as a deubiquitinating enzyme. {ECO:0000269|PubMed:17696782, ECO:0000269|PubMed:21118805, ECO:0000269|PubMed:23625928}.