2171
In contrast to PMA , RA did not induce any CAT activity in these cells, thus suggesting that the RA -induced changes in the expression of those genes described above were not dependent on the AP-1 enhancer activity .
 ( protein: AP-1, None) , ( DNA: AP-1 enhancer, None) , ( protein: CAT, 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: AP-1, None) , ( DNA: AP-1 enhancer, None) , ( protein: CAT, None) 