1872
Electrophoretic mobility supershift assays determine that members of the NF-kappa B /Rel family of transcription factors can bind to this site in vitro and that DNA-binding complexes that contain p50 , p52 , p65 , and cRel correlate with positive regulation whereas the presence of p50 correlates with negative regulation .
 ( protein: p50, None) , ( protein: p52, None) , ( protein: p50, None) , ( protein: cRel, None) , ( protein: NF-kappa B /Rel family, None) , ( protein: DNA-binding complexes, None) , ( protein: NF-kappa B, None) , ( protein: transcription factors, None) , ( protein: p65, 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: p50, None) , ( protein: p52, None) , ( protein: p50, None) , ( protein: cRel, None) , ( protein: NF-kappa B /Rel family, None) , ( protein: DNA-binding complexes, None) , ( protein: NF-kappa B, None) , ( protein: transcription factors, None) , ( protein: p65, None) 