6471
Restoration of terminal differentiation in the mouse erythroleukemia ( MEL ) cells requires a decline in the level of PU.1 , indicating that PU.1 can block erythroid differentiation .
 ( cell line: MEL, None) , ( cell line: mouse erythroleukemia ( MEL ) cells, None) , ( protein: PU.1, None) , ( protein: PU.1, 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: MEL, None) , ( cell line: mouse erythroleukemia ( MEL ) cells, None) , ( protein: PU.1, None) , ( protein: PU.1, None) 