The rate of cellular movement in the crypt column.

<p>A: The left panel shows the distribution of the number of mitoses needed to push a cell at position <i>i</i> out of the crypt column for each proliferation curve. Colors match the corresponding proliferation curves in <a href="http://www.ploscompbiol.org/article/info:doi/10.1371/journal.pcbi.1003082#pcbi-1003082-g001" target="_blank">Fig. 1C</a>. The horizontal axis represents the position of the cell in the crypt. Box plots indicate the distribution of the number of mitoses, assuming no cell death. The size of each bar indicates the amount of variation in the number of cell divisions. The right panel provides a zoomed-in view focusing on curves 1, 2 and 3. B: The effects of cell death on cellular movement in the crypt for three selected representative positions (2, 12, and 22) in the crypt column under the assumption of a uniform death selection function. As the death rate, <i>λ</i>, increases, the rate of cell movement increases, as shown by the decreasing number of mitoses needed to push a cell out of the crypt column. C: The panel shows the effects of cell death on the mitotic stress of the stem cell assuming a uniform death selection function. The average number of times the stem cell is selected for divisions is displayed as a function of cell death for the proliferation kinetic curves. Without cell death, the number of times the stem cell is selected for cell division is identical for all curves. As <i>λ</i> increases, the mitotic stress on the stem cell increases. The magnitude of increase depends on the shape of proliferation kinetic curve. Dots represent results from simulations, whereas the lines are exact results based on the terms inside the parentheses in <a href="http://www.ploscompbiol.org/article/info:doi/10.1371/journal.pcbi.1003082#pcbi.1003082.e050" target="_blank">Eq. 8</a>. All graphs are generated based on 1,000 simulations for each kinetic curve under each scenario. All cells are assumed to have identical relative fitness values.