Anti–BCR-ABL AS-ODNs inhibit p210^BCR-ABLexpression. CML CD34⁺ cells from a patient with a known b₃a₂ BCR-ABL splice site were incubated in serum-free medium with addition of either breakpoint-specific antisense ODNs (AS) or with b₃a₂ specific missense ODNs (MS) for 48 hours as described in the legend. mRNA obtained from 20 × 10³ cells was used for RT-PCR for either the BCR-ABL mRNA or β-actin (top panel). Protein extracts obtained from 1 × 10⁶ cells were subjected to SDS-PAGE and Western blotting with an anti–c-ABL antibody (Ab3) as described in Materials and Methods (bottom panel).