1
Activation of the CD28 surface receptor provides a major costimulatory signal for T cell activation resulting in enhanced production of interleukin-2 ( IL-2 ) and cell proliferation .
 ( protein: CD28, None) , ( protein: CD28 surface receptor, None) , ( protein: IL-2, None) , ( protein: interleukin-2, 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: CD28, None) , ( protein: CD28 surface receptor, None) , ( protein: IL-2, None) , ( protein: interleukin-2, None) 