MLL rearrangement in leukemic cells from patients with ALL. Genomic DNA was digested with BamHI or EcoRI restriction enzymes, separated by electrophoresis, blotted to nylon membranes, and hybridized with the radiolabeled P/S4 probe. (A) Probes for analysis of MLL gene rearrangement. Partial restriction map of the 11q23 region containing the MLL gene. Approximate positions of MLL exons 4 through 13 (of 21 exons) are shown as gray boxes. Areas mapped by probes P/S4, 98.40, and 4.2E are indicated. Abbreviations: H, HindIII; E, EcoRI; B, BamHI; S, Sac I. (B) BamHI digest. (C) EcoRI digest. RS4;11 cells were used as a positive control and normal peripheral lymphocytes served as a negative control. bp, base pairs.