UBB and neoplasm: Indeed, deregulation of the ubiquitin system is often observed in tumor-suppressing pathways (e.g. overactivation/expression of an E3 ligase leading to the ubiquitin-dependent degradation of a protein with tumor suppressive function) as well as tumor-promoting pathways (e.g. inactivation of an E3 ligase leading to the stabilization of oncoproteins).