Neural precursor cell-expressed developmentally down-regulated 8 (NEDD8), a ubiquitin-like protein,mainly functions through covalent ligation to cullin proteins. Conjugation of NEDD8 with cullins can promoteubiquitination, which plays a critical role in the degradation of many proteins. UBA3 is the subunit of NEDD8-activating enzyme which is one of the keys for NEDD8 linkage to cullin proteins. Previous research showedNEDD8 conjugation to be up-regulated in highly proliferative cell lines. In the present study, up-regulated NEDD8conjugation was observed in melanoma cell lines by Western blot analysis. After down-regulation with a RNAi toUBA3, proliferation of M14 was suppressed in vitro and in vivo. In conclusion, up-regulated NEDD8 conjugationmay be involved in the development of melanoma. Interference in this pathway might offera promising methodfor melanoma therapy.