Induction of CD95-mediated apoptosis in LCL cells. pRT-1-IκBα_S32,36A–transfected (upper panel) or pRT-1-STAT1β–transfected (lower panel) cells were pretreated with (+) or without (-) doxycycline for 36 hours. Cells were maintained ± doxycycline and additionally treated with the anti-CD95 agonistic mAb BG27 for 24 hours or left untreated. Percentage of annexin V–positive cells is indicated in each graph. Results were confirmed by quantification of sub-G1 peak of cells (not shown).