Bz 423 is a pro-apoptotic 1,4-benzodiazepine with therapeutic properties in murine models of lupus demonstrating selectivity for autoreactive lymphocytes, and activates Bax and Bak. In Vitro: Bz-423 induces a larger superoxide response in Ramos cells, and causes rapid death of Ramos B cells. Bz-423 activates Bax and Bak, but does not activate ASK1/JNK in Ramos cells. In Ramos cells Bz-423-induced superoxide leads to Bax and Bak activation via changes in Mcl-1 expression and functional activation of BH3-only proteins^[1]. Bz-423 rapidly increases superoxide levels in MEFs within 1 h and the magnitude of the increase is concentration-dependent. Bz-423-induced apoptosis dependents upon superoxide^[2].