CD40-mediated protection of BJAB cells against Fas-induced killing requires NF-κB. PI nuclear staining of BJAB cells (A) stimulated with anti–APO-1 for the times indicated or (B) for 21 hours in the presence (+) or absence (–) of sCD40L treatment. (C) PI nuclear staining of BJAB cells transduced with MIGR1-IκBαM (▦) or empty MIGR1 (▪) as shown and treated for 21 hours with anti–APO-1, with (+) or without (–) sCD40L as in (B). Cells were sorted by FCM prior to stimulation and were > 95% GFP⁺. (A-C) Values express percent viability relative to untreated cultures and represent the mean ± standard deviation of 3 independent experiments.