4356
The nature of CD40 -dependent signals in proliferating fresh human Epstein-Barr virus -negative B lymphocytes is currently unknown.
 ( cell line: human Epstein-Barr virus -negative B lymphocytes, None) , ( protein: CD40, 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: human Epstein-Barr virus -negative B lymphocytes, None) , ( protein: CD40, None) 