The deregulation of E3 ligases contributes to cancer development and their overexpression is often associated with poor prognosis, as has been shown in studies of inhibitor of apoptosis protein (IAP)-family genes (33), murine double minute 2 (Mdm2) (34), Casitas B-lineage lymphoma (CBL)-family proteins (35) and anaphase promoting complex (APC) (36). This evidence concerns the gene MDM2 and cancer.