13937
The biological effects of RA are mediated by two distinct families of transcription factors : retinoic acid receptors ( RARs ) and retinoid X receptors ( RXRs ).
 ( protein: RARs, None) , ( protein: transcription factors, None) , ( protein: retinoid X receptors, None) , ( protein: RXRs, None) , ( protein: retinoic acid receptors, 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: RARs, None) , ( protein: transcription factors, None) , ( protein: retinoid X receptors, None) , ( protein: RXRs, None) , ( protein: retinoic acid receptors, None) 