451
We have begun to examine the structure of the B2 subunit promoter region .
 ( protein: B2 subunit, None) , ( DNA: promoter region, None) , ( DNA: B2 subunit promoter 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:
 ( protein: B2 subunit, None) , ( DNA: promoter region, None) , ( DNA: B2 subunit promoter region, None) 