Effects of ZTP on cellular viability and morphology in human breast cancer MCF-7 cells. Cells were treated with or without different concentrations of ZTP at 0 μg/mL, 10 μg/mL, 50 μg/mL, 100 μg/mL, 200 μg/mL, and 400 μg/mL for 24 hours, 48 hours, and 72 hours, and then the cell viabilities of (A) MCF-7 cells and (B) the normal human breast cells (MCF-10A) were assessed by MTT assay. Data represent mean ± SD of three independent experiments. (C) MCF-7 cells in response to various concentrations of ZTP for 48 hours showed morphological changes, which indicated ZTP-induced cell death (original microscope magnification, 200×). * p < 0.05 indicates statistically significant difference versus the control group. ** p < 0.01 indicates statistically significant difference versus the control group. MTT = 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide; SD = standard deviation.