Fig. (2) (A) Bulk caspase 8 deficient I9.2 cells were stably transfected with either WT procaspase 8 (WT casp8) or procaspase 8 containing the F355R F356N mutant (casp8 RN), and expression of the transgene confirmed by immunoblot for procaspase 8. (B) Bulk 19.2 cells stably transfected with GFP, GFP wild-type caspase 8, or GFP RN mutant caspase 8 were treated with Tat, Fas ligation, gp120, TNF, TRAIL, Vpr peptide, H₂0₂, or transfected with HIV protease and analyzed for death specifically in the GFP positive cells.