Figure 3.

Effect of compounds 28, 1a, and cyclosporine A (CsA) on ABCB1-mediated resistance to paclitaxel in ABCB1 overexpressing drug selected (A) and transfected (B) cell lines. (A) Concentration-dependent curves of paclitaxel with or without compounds 28, 1a, and CsA at 3 μM in parental SW620 and ABCB1 overexpressing SW620/Ad300 cells. The IC₅₀ values of SW620/Ad300 cell line were compared with those of parental SW620 cells (see Table 2). (B) Concentration-dependent curves of paclitaxel with or without compounds 28, 1a, and CsA at 3 μM in parental HEK293/pcDNA3.1 and ABCB1 overexpressing HEK/ABCB1 cells. The IC₅₀ values of HEK/ABCB1 cell line were compared with those of parental HEK293 cells (see Table 2). Points with error bars represent the mean ± SEM. The figure is a representative of four independent experiments, each done in triplicate.