12853
Thirty percent of GC B cells , but not naive B cells , displayed mutations in the 742 bp region analyzed within the first intron of BCL-6 (overall frequency: 5 x 10(-4)/bp).
 ( cell type: GC B cells, None) , ( cell type: naive B cells, None) , ( protein: BCL-6, None) , ( DNA: 742 bp region, None) 
Locate the role in the text that participated in the event based on the event type and return it in the event list. 
 Option: Event type: RNA,cell type,protein,cell line,DNA, Arguments type: . 
Text: {0} 
Answer:
 ( cell type: GC B cells, None) , ( cell type: naive B cells, None) , ( protein: BCL-6, None) , ( DNA: 742 bp region, None) 