Fig. 2.
The observed clone size distribution is reproduced by a stochastic model. The data points (blue) show the size distribution associated with the 129 clones with three or more cells. If we assume that the balance between proliferation and differentiation is determined stochastically, with RPCs dividing with a fixed probability PPP=0.055 of adopting P/P cell fate, PPD=0.221 of adopting P/D cell fate, and PDD=0.724 of adopting D/D cell fate, we obtain the clone size distribution given by the red curve. The error bars on the theoretical curve denote 95% confidence intervals and are a result of the finite sample size. Since the probability of adopting the P/P cell fate is small, the size distribution is close to exponential, reflecting the fact that the majority of clones can be described by a sequence of asymmetric P/D divisions terminating in a D/D division.