Genetic Toggle Switch Without Cooperative Binding
  Genetic switch systems with mutual repression of two transcription factors are studied using deterministic and stochastic methods. Numerous studies have concluded that cooperative binding is a necessary condition for the emergence of bistability in these systems. Here we show that for a range of biologically relevant conditions, a suitable combination of network structure and stochastic effects gives rise to bistability even without cooperative binding. 
Azi Lipshtat, Adiel Loinger, Nathalie Q. Balaban and Ofer Biham