CACUL1 and cancer: Although the cullin family members are the best-known and studied neddylation targets, other non-cullin proteins including various transcription factors such as tumor protein 53 (TP53), tumor protein 73 (TP73) and E2F have been recently shown to be tagged with NEDD8 and dysregulation of the neddylation appears to be one of the hallmarks of cancers [23].