9741
Activation of mature B cells via Ag receptor cross-linking induces transient expression of the transcription factor Egr-1 .
 ( cell type: B cells, None) , ( protein: transcription factor, None) , ( protein: Ag receptor, None) , ( protein: Egr-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 type: B cells, None) , ( protein: transcription factor, None) , ( protein: Ag receptor, None) , ( protein: Egr-1, None) 