11865
Furthermore, we demonstrate that binding of several B cell-specific transcription factors , essential for IgH 3' enhancer activity , is lacking, which may explain 3' enhancer inactivity , although the binding of repressors cannot be excluded.
 ( protein: transcription factors, None) , ( DNA: IgH 3#$%# enhancer, None) , ( protein: B cell-specific transcription factors, None) 
Locate the role in the text that participated in the event based on the event type and return it in the event list. 
 Option: Event type: RNA,cell type,protein,cell line,DNA, Arguments type: . 
Text: {0} 
Answer:
 ( protein: transcription factors, None) , ( DNA: IgH 3#$%# enhancer, None) , ( protein: B cell-specific transcription factors, None) 