Figure 5.

Stochasticity maintains phenotypic diversity in cell populations. (A) Cancer cell subpopulations [stem cell-like cells (SL; red), basal (green), and luminal (blue)] were sorted using fluorescence-activated cell sorting (FACS) to isolate cell type specific populations. After 6 days post-sorting, each of the isolated populations expanded to contain all three cell subtypes, suggesting that all three cell types can interconvert stochastically between different cell states. (B) Graph showing the proportion of SL, basal, and luminal cells in two cancer cell lines before sorting. (C) Cells were FACS sorted to produce populations with a single pure cell type. The graph shows the that 6 days after sorting the proportion of SL, basal, and luminal cells in each of these populations has returned nearly to the starting proportions. (D) Schematic diagrams depicting the stochastic cell state transitions between cell types for each cell line. Reprinted from Cell, 146/4, Gupta et al. (2011) Copyright, with permission from Elsevier. (E) A probabilistic model for the endoreduplication of a population of Arabidopsis epidermal cells. A 2C cell (blue) may either randomly decide with the probability p1 to either enter endoreduplication or mitotically divide. If the cell enters endoreduplication in the first cell cycle, it will continue to endoreduplicate until it becomes a 16C giant cell (red). If the cell undergoes mitotic division, then each daughter cell has a random probability p2 of entering endoreduplication. If a cell enters endoreduplication in the second cell cycle, then it will continue to endoreduplicate until it becomes an 8C cell (purple), whereas if it mitotically divides, then each daughter cell will once again have a random probability p3 of entering endoreduplication or dividing. If in the third cell cycle a cell enters endoreduplication, then it will become a 4C cell (green), whereas if it doesn't it will remain a 2C (blue) cell. Those final 2C cells have the probability ps to become a stomatal cell (yellow). This figure is reprinted from Roeder et al. (2010) under the Creative Commons Attribution license.