Figure 4

Parameter sensitivity analysis of the “ON” fixed point of the core NANOG circuit. a: Each model parameter was changed by 20 and 40% and the obtained new steady states (blue circles) are overlayed on the phase space plot of Additional file 1: Figure S1d. Of particular interest is a change in C _Nanog,OS, the increase of binding energy of RNAP II at the Nanog promoter in the presence of the OCT4/SOX2 dimer. Twenty percent change in this parameter shifts the equilibrium NANOG concentration by more than an order of magnitude more than that of OCT4 (black circle). b: Parameter dependence of nullclines and fixed points: the orange and cyan curves were obtained in a simulation with increased C _Nanog,OS. Notice that in the “ON” state, NANOG concentration is increased by a factor of 2, while OCT4 levels remained the same. Furthermore, the altered set of parameters excludes the “OFF” state of the system. Concentrations are presented in the units of nM.