The DCN1-like protein family is comprised of Dcun1D1, Dcun1D2, Dcun1D3, Dcun1D4 and Dcun1D5. The founding member, Dcun1D1, is involved in the malignant transformation of squamous cell lineage.Dcun1D4, (defective in cullin neddylation protein 1-like protein 4 or DCN1-like protein 4), also designated KIAA0276, exists as 2 isoforms as a result of alternative splicing and contains one DCUN1 domain. The gene encoding Dcun1D4 maps to chromosome 4, which houses nearly 6% of the human genome and has the largest gene deserts (regions of the genome with no protein encoding genes) of all of the human chromosomes. Defects in some of the genes located on chromosome 4 are associated with Huntington's disease, Ellis-van Creveld syndrome, methylmalonic acidemia and polycystic kidney disease.