Fig. 1.

Modeling event timing as an FPT problem. (Left) Schematic depicting a gene transcribing mRNAs, which are further translated into proteins. The transcription rate is assumed to be regulated by the protein level, creating a feedback loop. (Right) The timing of an intracellular event is formulated as the FPT for the protein level to reach a critical threshold. Sample trajectories for the protein level over time obtained via Monte Carlo simulations are shown, and they cross the threshold at different times due to stochasticity in gene expression. The histogram of the event timing is shown on the top.