4227
These findings establish that STAT1 and STAT5 , and possibly STAT3 , are activated upon stimulation of precursor B cells with IL-7 .
 ( cell type: precursor B cells, None) , ( protein: IL-7, None) , ( protein: STAT1, None) , ( protein: STAT3, None) , ( protein: STAT5, 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:
 ( cell type: precursor B cells, None) , ( protein: IL-7, None) , ( protein: STAT1, None) , ( protein: STAT3, None) , ( protein: STAT5, None) 