7181
CTLA-4 engagement by mAbs inhibits, while CD28 enhances, IL-2 production and proliferation upon T cell activation .
 ( protein: IL-2, None) , ( protein: CTLA-4, None) , ( protein: mAbs, 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: IL-2, None) , ( protein: CTLA-4, None) , ( protein: mAbs, None) , ( protein: CD28, None) 