6882
These cells had properties of both natural killer ( NK ) and pre-T cells .
 ( cell type: pre-T cells, None) , ( cell type: NK, None) , ( cell type: natural killer, 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 type: pre-T cells, None) , ( cell type: NK, None) , ( cell type: natural killer, None) 