14720
To determine whether these different X1 box activities represented distinct DNA binding proteins or multimeric forms of the same factor(s), protease treatment of the crude nuclear extracts followed by DNA-binding assays were carried out and demonstrated that B cell extracts contain at least two X1-specific factors .
 ( protein: X1-specific factors, None) , ( protein: protease, None) , ( protein: DNA binding proteins, 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: X1-specific factors, None) , ( protein: protease, None) , ( protein: DNA binding proteins, None) 