4525
HIV-1 harboring mutations within two C/EBP sites were crippled in their ability to replicate in U937 promonocytic cells , indicating that these sites are required for replication.
 ( cell line: U937 promonocytic cells, None) , ( DNA: C/EBP sites, 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: U937 promonocytic cells, None) , ( DNA: C/EBP sites, None) 