9241
The natural dominant negative HLH factor Id3 , which blocks transcriptional activity of a number of known bHLH factors , was expressed in CD34+ progenitor cells by retrovirus-mediated gene transfer.
 ( protein: bHLH factors, None) , ( protein: Id3, None) , ( cell type: CD34+ progenitor cells, None) , ( protein: dominant negative HLH factor, 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: bHLH factors, None) , ( protein: Id3, None) , ( cell type: CD34+ progenitor cells, None) , ( protein: dominant negative HLH factor, None) 