Fig. 5

Tristability is possible in the mass action toggle switch models only when simulated stochastically. a The simple toggle switch with no autoregulation can be both bistable and tristable. The two posteriors are shown, plotted on the prior ranges, where the posterior distribution of the bistable switch is shown in blue and of the tristable switch in red. From the posterior distribution we can deduce the the dimerization parameter must be small for tristability to occur but large for bistability. b The switch with double positive autoregulation and its posterior distributions for the bistable and tristable case