Figure 3. Testing module robustness in silico. We used the Hill coefficient to evaluate the robustness of the MAPK module, because the Hill coefficient can be used to define the system output. Robustness was assessed in silico by determining how the Hill co-efficient was maintained in the face of random perturbations to the system. Here we display the box plot of the system outputs (i.e., the value of the Hill co-efficient) in the face of random perturbations.