Cell population simulations. Each subfigure was generated from 100 simulations, each representing a single cell with sixty time steps. Starting from the top left frame to the right bottom frame the degradation propensity for DNA damage was increased by 5%, i.e. (top left), (top right), (bottom left), and (bottom right). The x-axis represents discrete time steps and the y-axis the average expression level. The initial state for all simulations was 0011. This figure shows that, if the intensity of the damage is increased more cells exhibit oscillations in the level of p53, in agreement with experimental observations .