1889
The effects of prostaglandin E2 ( PGE2 ) on cytokine production and proliferation of the CD4+ human helper T cell clone SP-B21 were investigated.
 ( cell line: CD4+ human helper T cell clone SP-B21, None) , ( protein: prostaglandin E2, None) , ( protein: cytokine, None) , ( protein: PGE2, 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 line: CD4+ human helper T cell clone SP-B21, None) , ( protein: prostaglandin E2, None) , ( protein: cytokine, None) , ( protein: PGE2, None) 