11595
We reported here that the E1B 19K mutant viruses were unable to replicate efficiently in a monocyte cell line , U937 .
 ( cell line: U937, None) , ( protein: E1B 19K, None) , ( cell line: monocyte cell line, 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, None) , ( protein: E1B 19K, None) , ( cell line: monocyte cell line, None) 