Representative time courses from the model. (A) Log_e (expression ratios) vs. time for all genes (shaded lines) and ligand (dashed line) from deterministic simulation in response to a pulse of ligand. (B) Comparison of stochastic and deterministic simulations for the unrepressed G promoter (P_GC) and the G transcript: P_GC and MG vs. time. Note that the stochastic simulation accounts for the fact that there can only be 0, 1, or 2 molecules of P_GC/cell at any given time.