4480
The human T-cell leukemia virus type 1 posttranscriptional trans-activator Rex contains a nuclear export signal .
 ( protein: nuclear export signal, None) , ( protein: Rex, None) , ( protein: human T-cell leukemia virus type 1 posttranscriptional trans-activator, 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: nuclear export signal, None) , ( protein: Rex, None) , ( protein: human T-cell leukemia virus type 1 posttranscriptional trans-activator, None) 