Table 1

Drug resistance of K562/BCRP cellsa

DrugIC50 (ng/ml)
Degree of resistance
SN-380.42 ± 0.0210 ± 0.324
Mitoxantrone0.33 ± 0.023.6 ± 0.211
Topotecan3.1 ± 0.130 ± 210
  • a K562 or K562/BCRP cells were cultured for 5 days with increasing concentrations of SN-38, mitoxantrone, or topotecan. Cell numbers were counted with a Coulter counter, and IC50 was determined. Degree of resistance is the ratio of IC50 for K562/BCRP cells divided by that for K562 cells. Data are represented as mean values ± SD from triplicate determinations.