Modest variability in 3′ PI phosphatase expression enhances wound invasion rate. In each plot, either 3′ PI phosphatase expression pmax was varied alone (open diamonds) or together with rmax (filled squares), emax (filled triangles), or both rmax and emax (stars) according to sampling models illustrated in Figure 3B. Penetration depth is defined as in Figure 3. Values are averaged over 50 independent model runs, and 95% confidence intervals are within 5% of the mean, except where the penetration depth approaches 5 mm. (A) model II, normal distribution. (B) model II, lognormal distribution. (C) model III, normal distribution. (D) model III, lognormal distribution.