A comparative study of apoptotic signalling in the context of Boolean and probabilistic Boolean networks. Background subtracted and normalised experimental data derived from Schlatter et al. is shown in the top box. The experimental data compare the activities of downstream signalling molecules and apoptotic activity in the control setting (no stimulation) versus two intensities of UVB irradiation (UVB_low, 300 J/m2 and UVB_high, 600 J/m2). The activities of caspase 3 refer to the high caspase 3 activities of the original publication. The steady-state values from the original BN and the steady-state probability of the molecules to be ON from the optimised PBN of one exemplifying run are shown in brackets. (Note: The interactions between each node in the actual network are much more complex than the simplified diagram as shown.).