Fig. 3

Effect of CpdA on PTX cytotoxicity. The cytotoxicity to PTX in the condition of cells with and without CpdA in (a and c) MDA-MB-231 and (b and d) MDA-MB-435. Numbers of viable cells were counted by trypan blue staining in (a) and (b) and by MTS assay in (c) and (d). The cell reduction after PTX treatment of CpdA-treated cells was compared to that of parental cells as controls represented as (a) and (b) for MDA-MB-231; (c) and (d) for MDA-MB-435 cells. *p-value < 0.05. Graphs represent mean ± SD of apoptotic cell counts identified by caspase-3/7 apoptosis assay at different time points of different treatments for (e) MDA-MB-231 and (f) MDA-MB-435. The 2–3 independent experiments were performed. *p-value < 0.05 compared to PTX treatment. Microscopic pictures of apoptotic cells are shown in according to the line graphs. Scale bar = 300 μm and original magnification 100X. The isobolograms represent the synergistic effect of CpdA to the cell killing effect of PTX in (g) MDA-MB-231 and (h) MDA-MB-435