B. The in vitro synthesized [35S]Met-labeled single-cysteine Bax proteins were activated and targeted to the mitochondria that were pretreated with NEM to block the sulfhydryls of mitochondrial proteins. The resulting mitochondria were isolated and oxidized by CuPhe for 30 min. NEM and EDTA were then added to stop the oxidation. For the "0 min" controls, NEM and EDTA were added before the addition of CuPhe. The resulting samples were analyzed by phosphor-imaging after non-reducing or reducing SDS-PAGE (see Appendix Figure S2A). 