Detection of BCL6 fusion transcripts by 5′ RACE analysis. RNA derived from tumors 1020, 352, and 1547 were subjected to reverse transcriptase (RT)-PCR amplification as described in the text. Arrows point to bands representing BCL6 chimeric transcripts. RNA from tumor 1562 (C), which showed no BCL6rearrangement by Southern blot analysis, was used as the negative control. The fragment size of the marker ◊X174 RF DNA/HaeIII is indicated.