4521
Previous work has shown that C/EBP sites and C/EBP transcriptional activators are necessary for HIV-1 LTR activity in monocytes/macrophages .
 ( DNA: C/EBP sites, None) , ( DNA: HIV-1 LTR, None) , ( cell type: monocytes/macrophages, None) , ( protein: C/EBP transcriptional activators, 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:
 ( DNA: C/EBP sites, None) , ( DNA: HIV-1 LTR, None) , ( cell type: monocytes/macrophages, None) , ( protein: C/EBP transcriptional activators, None) 