2552
A 500-bp fragment encompassing this hypersensitive site ( nt 4481 to 4982 ) exhibited transcription-enhancing activity (two- to threefold) when it was cloned in its natural position with respect to the HIV-1 promoter after transient transfection in U937 and CEM cells .
 ( DNA: 500-bp fragment, None) , ( cell line: U937, None) , ( cell line: CEM cells, None) , ( DNA: hypersensitive site, None) , ( DNA: nt 4481 to 4982, None) , ( DNA: HIV-1 promoter, 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: 500-bp fragment, None) , ( cell line: U937, None) , ( cell line: CEM cells, None) , ( DNA: hypersensitive site, None) , ( DNA: nt 4481 to 4982, None) , ( DNA: HIV-1 promoter, None) 