A snapshot of a two-cluster solution in the ensemble of n = 104 cells represented on a unit circle. The coupling function is f(I) = −0.5I. The signaling region is S = [r2, s] and the responsive region is R = [r1, r2] with r1 = 0.3, r2 = 0.65 and s = 0.95. Positions of the cells are indicated by grey circles and black triangles. Cells within clusters are spread because of Gaussian noise (the SDE model) added to the system.