Fluctuations in protein concentrations and gene expression driven by a noise. Fluctuations in protein concentrations (a) and gene expression (c), driven by a noise (b) added to the autocrine ligand decay parameter δ
FGF, which changes its value by ±30%. In the time series regimes with high and low NANOG concentration were identified, using threshold concentrations of 1.0 nM and 0.7 nM for NANOG high and low expression, respectively. The corresponding time-averaged expression levels are plotted in panel (d).