(A) Expression of mdr1 mRNA on AML blast cells (Case No. 9) after random or MDR1-AS treatment (2.5 μmol/L) by RT-PCR analysis. The ratio ofmdr1/β2-microglobulin in random- and MDR1-AS–treated groups analyzed by scanning densitometry were 2.06 and 0.55, respectively. (B) Expression of mdr1 mRNA of cells from pooled colonies produced by AML blast cells (Case No. 9) treated with random or MDR1-AS oligonucleotide by RT-PCR analysis. The ratio ofmdr1/β2-microglobulin in random- and MDR1-AS–treated groups analyzed by scanning densitometry were 0.93 and 0.58, respectively.