Washout probabilities upon mis-regulated Wnt and Hippo signalling activity. (a, b) Washout probabilities for APC double-mutant crypt, starting from a single mutant cell introduced at the base of the crypt (bottom 5% of crypt) using (a) externally-imposed gradient (ME1) or (b) cell-division based (MI) Wnt models. Blue and red lines represent the low (40% Wnt threshold/10% Wnt reservoir) and high (100% Wnt threshold/20% Wnt reservoir) Wnt cases, respectively. Increasing the volume threshold for CI reduces the probability of mutant washout. Shaded regions represent 95% confidence intervals for a binomial distribution with probability , according to , where is the number of simulations conducted, and is the 97.5 percentile of a standard normal distribution. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)