Figure 1

Development of drug resistance in U-2OS and Saos cell lines during paclitaxel treatment. (A) The time course of development of paclitaxel resistance in U-2OS cell line in the absence or in the presence of 1 μ M NSC23925. (B) The time course of development of paclitaxel resistance in Saos cell line. Two independent experiments were established simultaneously in cells selected with paclitaxel alone, and resistance U-2OS and Saos cell lines developed on both occasions (paclitaxel-1 and paclitaxel-2). The experiments of cells cultured with the paclitaxel–NSC23925 combination were also repeated independently two times, in which the use of NSC23925 prevented the development of resistance to paclitaxel on both occasions (paclitaxel–NSC23925-1 and paclitaxel–NSC23925-2). Different selection points for cell sublines indicated by arrows in the time course of paclitaxel-1 and paclitaxel–NSC23925-1 were used in the further experiments.