9169
In the absence of tetracyclines , the transfected T cells were shown to express the chimeric receptor on the cell surface and could be activated by its cognate Ag , leading to the secretion of IL-2 .
 ( protein: cognate Ag, None) , ( cell type: T cells, None) , ( protein: IL-2, None) , ( protein: chimeric receptor, 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: cognate Ag, None) , ( cell type: T cells, None) , ( protein: IL-2, None) , ( protein: chimeric receptor, None) 