Validation of predicted breakpoints in patient samples by PCR and Sanger sequencing. (a) Amplified junctional DNA fragments using CML DNA from patients 1, 2, or 3 as template. PCR with primer sets (PhS1F9, R9 and PhS1F2.2, R2.2) successfully amplified a DNA fragment from patient 1 DNA (lanes 2 and 4) but not from patient 3 (lanes 10 and 11). Primer sets (PhS2F1.1, R1.2 and PhS2F2.2, R2.2) gave a product from patient 2 DNA (lanes 6 and 8). The junctional DNA fragment was not detected using genomic DNA from normal lung tissue (lanes 3, 5, 7, and 9). Asterisks indicate unique fragments observed in patients' samples. (b) Each PCR-amplified DNA fragment was cloned into a plasmid vector and sequenced. Solid lines enclose the BCR region and broken lines enclose the ABL1 region.