Figure 3.

Southern blot analysis of switch regions in two MM cell lines. Genomic DNA from two cell lines was digested with the indicated restriction enzyme, and Southern blots were analyzed sequentially with various switch probes as described in Fig. 2. The probe is indicated above each lane. (A) MM-M1 cell line. (B) KMM-1 cell line. Illegitimate switch recombination fragments are indicated by 8 and 21 (corresponding to the chromosome involved in the recombination). Productive recombination fragments are indicated by a p.