Altering the initial signal amplitude shifts the I and A curves, but does not affect their shape.

<p>The four sets of curves were generated using initial concentrations of 10, 20, 50, and 100 molecules of pSTAT3, respectively. For each initial concentration, the maximum amount of I and A observed in 1000 time course trajectories measured out to 2000 min was compared to an arbitrary threshold and the percentage of trajectories crossing the threshold was computed for a wide range of signal degradation rates. The I threshold was set to 100 molecules, while the A threshold was set to 20 molecules. The results were generated using Model 1 and the parameters were obtained from <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0033018#pone-0033018-t001" target="_blank">Table 1</a> unless otherwise noted.