Phase portrait of stochastic simulation at a particular nuclear position. The time-evolution of the expression level of different gene combinations at a particular nuclear position is shown for the same circuits as in Fig.1. For comparison, the deterministic model is plotted using a solid red line and all stochastic runs (100) with light coloured lines. At the end of these lines a dot is plotted, which represents the final concentrations at T = 68.1 min. These end points were used to extract two clusters (with k-means clustering), which are represented by blue and green colours. The left panels show circuits with final points and pathways very close to deterministic model and the right panels show less well defined circuits.