Targeted degradation of bcr-abl mRNA in CML cells as determined by RT-PCR. RT-PCR products from bcr-abl and β-actin mRNAs were separated on agarose gels and stained with ethidium bromide. ODNs (as indicated in the figure) were added twice daily to CML cells from (A) patient 1 (5 μmol/L per treatment) or (B) patient 2 (2 μmol/L per treatment) for 2.5 days before isolation of RNA. The images show the PCR products stained with ethidium bromide in 1.2% agarose gels.