Before revision: Positive feedback in biochemical networks can lead to a bifurcation in state space. Universality implies that if molecules are well mixed, this bifurcation should exhibit the critical scaling behavior of the Ising universality class in the mean-field limit.
After revision: We make rigorous the notion of universality in well-mixed stochastic models of biochemical feedback, namely that they scale near their bifurcation point according to the exponents of the mean-field Ising universality class in the mean-field limit.