Model topology.

The model of CD95 network comprises the cytosol (blue), surrounded by the cell membrane, and the nucleus (orange). The subnet of this model is CD95 DISC (gray). The CD95 DISC comprises CD95, FADD, and DED chains/filaments. Procaspase-8, c-FLIPL, and c-FLIPR+S contribute to the DED chain/filament formation and embody the source of extrinsic noise (green). In contrast intrinsic noise is introduced by stochastic gene expression (yellow arrows). The relative amounts of procaspase-8, its cleavage products, and c-FLIP proteins were measured by western blot (thick frame), while active caspase-3 and nuclear NF-κB by imaging flow cytometry (red). Inhibitions are marked by red lines and activations by green arrows.