Transcriptional Dynamics of the Embryonic Stem Cell Switch
Figure 4
Steady State Behavior of OCT4–SOX2 and NANOG Concentration Levels as a Function of the Signal B−
The system is a bistable switch with respect to the B− concentration. As the threshold is crossed (B ≈ 36, arbitrary units), NANOG turns off, and OCT4 and SOX2 are reduced to lower levels. Since the signal is still present (A+ = 100), the OCT4 and SOX2 levels do not decline to very low levels.