CD44 and breast cancer: The percent inhibition of cell proliferation of the sorted CD24+‐breast cancer cells and CD24−/CD44+‐breast CSC populations in the presence of combinatorial treatment of doxorubicin (0.01 μM) and 1e (5 μM) was observed to be increased by 6.1‐folds in CD24−/CD44+ breast CSC population and 1.8‐folds in CD24+ cancer cells as compared with doxorubicin (0.01 μM) treatment alone (Figure 3A).