(A)Symmetric Stem Cell Replication and Cancer
Figure 3
(A) In the absence of mutant SCs, normal SC homeostasis is maintained in the stochastic process, and the abundance of normal SCs, n = 1,000, remains constant. Transition probabilities are pb = qb = 1/3.
(B) If a neutral mutant SC appears (i.e., a cell with the same reproductive fitness as a normal SC), random drift may allow the population to expand and take over the SC compartment (red) (pa = pb = qa = qb = 1/3, a0 = 1, b0 = 999, r = 1, averaged over 1,000 runs and the percentage plotted). As the probability for self-renewal of the mutant SC increases, a higher fraction of compartments are taken over by the mutant SC (green, pa = qa = 0.3; magenta, pa = qa = 0.25; black, pa = qa = 0.2; blue, pa = qa = 0.1; yellow, pa = qa = 0).
(C) A mutation that increases both the probability of self-renewal and the fitness is fixed in a large fraction of runs (red, pa = pb = 0.25, qa = qb = 1/3, a0 = 1, b0 = 999, r = 1.1; blue, pa = pb = 0.15, r = 1.3 averaged over 1,000 runs and the percentage plotted).