Figure 2.

MSF cDNAs used for sequencing. A chimeric RT-PCR product of MLL exon 5 (gray box) fused with unknown sequences initially was isolated. blast search showed that these sequences were identical to a portion of EST54371 (GenBank accession no. 347984), but did not exactly match any known genes. This EST was sequenced; 112 bp matched with the RT-PCR sequence exactly and extended it 1,023 bp downstream 3′. To obtain the sequence upstream of the breakpoint, we performed 5′ RACE using cDNA of the leukemia cell line K562 as template and MSFR4 in MSF as the primer. 5′ RACE yielded a 1.4-kb product that had sequences overlapping the initial sequence obtained from RT-PCR. Arrows show location of the primers used in this study. The numbers indicate the nucleotide positions shown in Fig. 5.