4758
Stimulation of U1 cells by LPS alone induced minimal levels of HIV expression , which was significantly enhanced by granulocyte-macrophage colony-stimulating factor ( GM-CSF ).
 ( cell line: U1 cells, None) , ( protein: GM-CSF, None) , ( protein: granulocyte-macrophage colony-stimulating factor, 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: U1 cells, None) , ( protein: GM-CSF, None) , ( protein: granulocyte-macrophage colony-stimulating factor, None) 