Cytotoxicity of Hst, Dox, and Their Combination on MCF-7/HER2 Cells. The 1.5x103 MCF-7/HER2 cells were seeded into 96 well plates and treated with Hst, Dox, and the combination on the following days. The cytotoxic assay was performed using the MTT method, as described in methods. (A), Percentage of cell viability after a single treatment of Hst and Dox at various concentrations for 24 h. Profiles of cell viability were expressed as mean ± SD from 3 independent experiments; (B), Change of cells morphology after Hst and Dox treatment for 24 h. Arrows indicate changes in each cell morphology; (C), Effect of the combination of Hst and Dox treatment on cell viability; (D), Index combination value; (E), Combination index plot, and (F), Isobologram for a combination of Hst and Dox measured by CompuSyn® software based on Chou-Talalay method