4481
The Rex protein of human T-cell leukemia virus type 1 is required for the nuclear export of unspliced viral mRNA and, therefore, for virus replication.
 ( protein: Rex protein, None) , ( RNA: unspliced viral mRNA, None) , ( protein: Rex, 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:
 ( protein: Rex protein, None) , ( RNA: unspliced viral mRNA, None) , ( protein: Rex, None) 