In vitro de-neddylation by NEDP1 is sensitive to oxidation. Poly-NEDD8 reactions were prepared with NAE, UBE2M, and NEDD8 as in Figure 1E. NEDD8 reactions were stopped by the addition of NAE inhibitor MLN4924 (3 μM). NEDD8 reactions were incubated with GST-NEDP1 at 30°C for the indicated amount of time under reducing (50 μM DTT) or oxidizing conditions (50 μM DTT + 150 μM H2O2). Reactions were stopped by the addition of LDS sample loading buffer and resolved by SDS-PAGE before processing for Western blot analysis with the indicated antibodies. 