U0126 and AZD6244 increased intracellular doxorubicin accumulation. A: HepG2 or Huh7 cells were treated with U0126 or AZD6244 for 48 hours, followed by incubation of doxorubicin (6 μg/ml) for 2 hours. Then the cells were trypsinized and resuspended in PBS followed by FACS analysis. B: Statistical analysis of FACS results. * P<0.05 compared with control group.