Apoptosis after FasL stimulation in hepatocytes grown on collagen (shown on the right panels). A. SQUAD simulation of apoptosis in hepatocytes. Activation values for network nodes are calculated and translated into concentration predictions. Maximum value is 1, minimum value is 0. Color code: Concentration curves for survival signals (grey), caspase-9 (beige), caspase-8 (dark blue), caspase-3 (green), cytochrome c release into the cytosol (black), resulting apoptosis (red), tBid formation (pink), Fas stimulation (light blue). B. Experimental data. Wildtype hepatocytes are cultured on collagen I and treated for 0-6 hours with 50 ng/ml N2A FasL. Lysates were fractionated into cytosol and mitochondria and were subjected to cytochrome c Western Blot analysis. Note that in collagen cultured hepatocytes, all cytochrome c remains in the mitochondria and is not released into the cytosol upon FasL treatment. Experimental data is given in the table. FACS analysis of GFP-annexin-V/PI stained wildtype primary hepatocytes plated on collagen, treated with 50 ng/ml N2A FasL for 0 to 4 hours. The values for the viable cells are given in a histogram.