5751
We conclude that CD28 costimulation can cause substantial T cell proliferation in the absence of IL-2 , which is driven by a soluble factor independent of NF-AT transactivation .
 ( protein: NF-AT, None) , ( protein: soluble factor, None) , ( protein: IL-2, None) , ( protein: CD28, 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: NF-AT, None) , ( protein: soluble factor, None) , ( protein: IL-2, None) , ( protein: CD28, None) 