Reciprocal IgH/c-myc translocations in CXP lymphoma. (A) SKY, FISH, and chromosome paint analyses (Chr12 pink, Chr15 green) for IgH/c-myc translocations in CXP163 and CXP153. A 3′ IgH BAC (light green) and a c-myc BAC (light green) were used in combination with chromosome paints to detect t(12;15) translocations. The t(15;12) translocation, not detectable by SKY, was visualized using the 5′ IgH BAC (pink) and a Chr15 paint (green). At least 15 metaphase spreads were analyzed for SKY, FISH, and chromosomal paints, respectively, for each CXP tumor. Translocations shown were observed in the majority of metaphases, and were scored as clonal if observed in >80% of metaphases. (B) Schematic of IgH/c-myc translocation breakpoint junctions cloned and sequenced from λ-phage tumor genomic DNA libraries. At least two independent phage clones were isolated from each genomic DNA library, and breakpoint junctions identified within them were further independently confirmed by PCR and sequencing from the appropriate tumor DNA samples. The numbers on the top indicate t(12;15) translocation breakpoints and the same numbers containing a (′) on the bottom indicate the “reciprocal” t(15;12) translocation breakpoints in the corresponding tumor: CXP153 (junction 1 and 1′), 163 (junction 2 and 2′), and 68 (junction 3′).