Figure 1. Dynamics of the model states and the sensitivity indices of the GATA1-PU.1 gene regulatory circuit model.

The states dynamics is shown on line A; the sensitivity dynamics for GATA1 gene is shown on line B and for PU.1 gene – on line C. The left panel corresponds to the simulation providing the steady-state solutions. Middle panel corresponds to the introduced perturbation (concentrations of GATA1 and PU.1 were changed at time  = 20) and shows system's recovery after the perturbation. Plots of right panel show system's critical transition after significant perturbation of the initial conditions introduced at time  = 20. Time is given in an arbitrary unit. Grey regions indicate the periods when the system is perturbed and the sensitivity pattern differs from the one at the beginning of the simulations. Grey regions of middle panel suggest that the perturbation was non-critical and faded after 4 time instances when the system recovered to its previous state, while the grey region of the right panel indicates the warning of system's critical transition showing that system did not recover after the introduced perturbation.