CD44 and cancer: Comparing simulation results with in vitro data demonstrated that neither (i) endowing normal and cancer stem cells with a lower radiosensitivity (i.e., a higher survival rate after irradiation), (ii) increasing the frequency of symmetric self-renewal division of stem cells, and (iii) increasing the rate of phenotypic reprogramming of surviving intact CCs to a full stem cell state, nor any combination of i, ii, and iii, were able to elevate the calculated stem cell percentage to match the observed percentage of CD44+/CD24−/low cells following an acute dose of 10 Gy.