Figure 8.

TNF-induced A-SMase processing and activation, in caspase-7 knockdown cells. (A) Down modulation of caspase-7 protein expression by siRNA analysed by western blotting and lack of TNF-induced caspase-7 activation in caspase-7 knockdown cells. (B) HeLa cells stably transfected with EGFP-tagged pro-A-SMase, or HeLa wild-type cells (C, D) were transfected with caspase-7 siRNA or control siRNA. Cells incubated with TNF for the indicated times were analysed by western blot with anti-GFP (B) or anti-A-SMase antibodies (C), respectively, and A-SMase activity assays (B, D). The knockdown of caspase-7 blocked the cleavage and activation of recombinant as well as endogenous pro-A-SMase, while they were unaltered in cells transfected with control siRNA.