(A) Bright-field microscopy images showing the ability of MDA-MB-231 cells to convert the MTT reagent to its formazan metabolite (dark granules and crystals) before (control) and after incubation with cisplatin (10 µM), oxaliplatin (10 µM), or paclitaxel (20 nM) for 3 days. Images were acquired after incubation of cells with MTT for ~1 h. (B) Percentages of polyploid/senescent giant cells and MTT-positive cells in cultures of the MDA-MB-231 cell line before (control) and after treatment with cisplatin (10 μM), oxaliplatin (10 μM), or paclitaxel (20 nM) for 3 days. Only adherent cells were evaluated. Bars, standard error (SE). (C) Effect of cisplatin treatment (3 days) on the extent of cell proliferation (determined by the direct cell counting assay) and cell membrane integrity (determined by the trypan blue-exclusion assay). Bars, SE. TB, trypan blue. (D) Response of MDA-MB-231 cells to cisplatin (3-day incubation with the indicated concentrations), evaluated by the 96-well plate XTT (solid squares) and CellTiter-Blue (open squares) “viability” assays. These images and data are reproduced from Mirzayans et al. [32,55].