(A) The percentage of P-gp⁺ cells in K562/ADM cells after oligonucleotide treatment (5 μmol/L). Determination of P-gp by fluorescence microscopy was performed after random (▧), MDR1-S (▧), and MDR1-AS (▩) treatment at various concentrations. The results are expressed as the percentage of treated cells compared with the untreated control, and represent the mean ± the SD of the three experiments. (B) Intracellular Rh123 retention in K562/ADM cells after oligonucleotide treatment (5 μmol/L). Intracellular Rh123 retention of untreated, random-, MDR1-S–, and MDR1-AS–treated cells was measured using flow cytometry, and the figure represents untreated and MDR1-AS–treated cells.