1571
One of these, previously called B1 , is a 97-kDa protein which is secreted in large amounts and has been purified from protein-free, conditioned medium .
 ( protein: B1, None) , ( protein: 97-kDa protein, 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: B1, None) , ( protein: 97-kDa protein, None) 