5451
This is the first description, to our knowledge, of regulatory elements that control expression of a gene encoding a B7 costimulatory molecule .
 ( protein: B7 costimulatory molecule, None) , ( DNA: regulatory elements, 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: B7 costimulatory molecule, None) , ( DNA: regulatory elements, None) 