13615
To differentiate whether the RA effect was mediated by RA receptors alpha , beta , and gamma , the expression of the retinoic acid receptors ( RAR ) was examined by reverse transcriptase -polymerase chain reaction ( RT-PCR ).
 ( protein: reverse transcriptase, None) , ( protein: retinoic acid receptors, None) , ( protein: RAR, 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: reverse transcriptase, None) , ( protein: retinoic acid receptors, None) , ( protein: RAR, None) 