Covalent attachment of NEDD8 to cullins, a process called neddylation, results in nuclear cullin accumulation, which promotes cell growth, migration, and transformation. DCUN1D3 inhibits neddylation of cullins by sequestering them to the plasma membrane, thereby promoting cell differentiation. Antagonizes DCUN1D1-mediated CUL1 neddylation by sequestering CUL1 at the cell membrane (PubMed:25349211). When overexpressed in transformed cells, may promote mesenchymal to epithelial-like changes and inhibit colony formation in soft agar (PubMed:25349211).