Effect of LY980503 at various concentrations on accumulation of intracellular DOX in SGC7901 and SGC7901/VCR cells. SGC7901 and SGC7901/VCR cells were incubated with 4.0 μmol/L DOX for 60 min, in the presence of 0.0, 1.0, 2.0, 4.0 and 10 μmol/L LY980503, respectively. Each point represents the mean ± SD from three experiments. bP < 0. 01 vs SGC7901 cells in the absence of LY980503; aP < 0.05, dP < 0.01 vs SGC7901/VCR cells in the absence of LY980503.