Effect of ABL and ABL-N on cancer cell lines. (a) The chemical structures of ABL and ABL-N. (b) The differences of growth inhibition activity between ABL and ABL-N in MDA-MB-231 cells. (c) Effects of ABL-N on the viability of various cancer cell lines. Cells were treated with ABL-N for 24 hours and cell viability was determined by the MTT assay. The IC50 is the concentration of ABL-N that reduced the cell viability by 50% under the experimental conditions (n = 6). (d) Time- and dose-dependent inhibition of cell viability by ABL-N treatment in MDA-MB-231, MCF-7, MDA-MB-468 and NBECs. Cells were treated with 5, 10, 20 or 40 μM ABL-N for 1, 3, 6, 12 and 24 hours and cell viability was assessed by MTT assay (n = 6). Results represent the means ± SE from three independent experiments.