背景
Ubiquitination,onetypeofthemostcommonposttranslationalmodification,mediatestheregulationofproteinhomeostasisinvivo.Sinceubiquitinits
elfcontainsmultiplelysineresiduesandoneNterminalfreeaminogroup,eighttypesofubiquitinchainscanbeformed.? K63-linked polyubiquitin
chains exert nonproteolytic functions in vivo, such as protein trafficking, kinase/phosphatase
activation, and DNA damage control, all of which might be important in regulation of cancer
survival and development （PMID: 19217402，PMCID: PMC3008764
