Combination of Taxol with oxamate shows synergistic inhibitory effects of Taxol-resistant and BT474 cells. A and B, 8 × 103 per well of 435TRP and 435TR1 cells were plated in 96-well plates and then treated with Taxol (Tax), Oxamate (Oxa) alone or Taxol plus Oxamate (Tax+ Oxa) with the indicated concentrations for 48 hrs. Cell viability was examined by MTS assay. Data are presented as the percentage of viability inhibition measured in cells treated without Tax and Oxa. C, BT474 cells were treated with Tax, Oxa alone or Tax plus Oxa with the indicated concentrations for 48 hrs.. Cell viability was measured by direct cell counting. Data are presented as the percentage of viability inhibition counted in cells treated without Tax and Oxa. D, 435TR1 cells were treated with 100 nM Taxol or/and 40 mM oxamate for 48 hrs, cell lysates were prepared and Western blotting were carried out with antibodies against total PARP (Top) or its cleaved protein c-PARP (Middle). β-actin was used as a loading control (Bottom). Columns, mean of three independent experiments; bars, SE. ***, P < 0.001.