3220
Recently, it has been shown that RelB knockout mice have no dendritic cells ( DC ).
 ( cell type: DC, None) , ( cell type: dendritic cells, None) , ( protein: RelB, 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: DC, None) , ( cell type: dendritic cells, None) , ( protein: RelB, None) 