Chestnut leaf extract-treated CSCs were more susceptible to Taxol treatment than untreated CSCs. Both MCF-7-derived CSCs (A) and their parental cells (B) were treated with chestnut leaf extract in the presence of Taxol at various concentrations (0, 0.1, 1, 10, 25, and 50 nM). The CSCs exposed to the extract became more vulnerable to Taxol at ≥1 nM, compared to the cells that were not exposed to the extract. CC, Castanea crenata leaf extract, 50 μg/mL. N = 3; error bars, mean ± SEM. Values not sharing common letter on bar indicate statistically significant difference from each other (p < 0.05).