801
The nuclear factor STAT-1 ( p91 ) was investigated by immunoprecipitation followed by immunoblotting for tyrosine phosphorylation .
 ( protein: nuclear factor STAT-1, None) , ( protein: p91, 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: nuclear factor STAT-1, None) , ( protein: p91, None) 