FISH analysis. Effect of BCR-ABL expression on DNA repair evaluated by FISH. Human parental UT-7/P (□) and BCR-ABL–expressing UT-7/9 (▪) cells were irradiated with 4 Gy and collected 24 hours later. A total of 200 metaphases were counted for each point. The figures represent the percentage of cells with chromosome 1 translocation.