ORC1 and neoplasm: Mechanistically, MLN4924 treatment inhibited cullin neddylation, inactivated Cullin-RING E3 ligases (CRLs), and led to accumulation of tumor-suppressive CRLs substrates, including cell cycle inhibitors (p21, p27, and WEE1), NF-κB signaling inhibitor IκBα, and DNA replication licensing proteins (CDT1 and ORC1).