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This is the first description of an HIV-2 enhancer element which displays such monocyte specificity, and no comparable enhancer element has been clearly defined for HIV-1 .
 ( DNA: enhancer element, None) , ( DNA: HIV-2 enhancer element, 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: enhancer element, None) , ( DNA: HIV-2 enhancer element, None) 