Fig. 1.

In the absence of drug, the population evolves to be mainly composed of highly proliferative cells. Sample dynamics of the population density n(x,t) (panel a) and the total number of cells ρ(t) (panel b) in the absence of xenobiotic agents (i.e., when c(·)=0), for the parameter values listed in Table 1. The initial condition corresponds to a population composed of different cellular clones [cf. Eq. (??)]. The inset of panel (b) displays the population density after 20 days [i.e., n(x,20)], which coincides with the equilibrium population density $\overline{n}\left(x\right)$ of Eq. (11)