4136
We propose that the requirement for precise spacing of the muA and muB elements is due in part to a directed DNA bend induced by PU.1 .
 ( protein: PU.1, None) , ( DNA: DNA bend, 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: PU.1, None) , ( DNA: DNA bend, None) 