signals in the two-module network (including the TetR/Ptet-based NOT gate) with constant CV noise model. A) OUTPUT1 signal for different noise entities, in response to 3OC6-HSL; in all the graphs, data points represent population-averaged values and error bars represent 95% confidence intervals. B) OUTPUT2 signal as a function of average OUTPUT1 in case of CV = 0.15. The average OUTPUT1 is computed from the 3OC6-HSL concentrations from panel A. Data points and error bars have the same meaning as above. Here, the cell-to-cell variability is derived from the propagation of noise from OUTPUT1. C) Population-averaged OUTPUT2 values as a function of average OUTPUT1. For all the CV values, data are fitted with a Hill function (solid line). The estimated parameters are reported in Table 2.