9519
RXR-alpha mRNA was present in untreated U937 cells , and levels increased after induction of differentiation with phorbol ester .
 ( protein: RXR-alpha, None) , ( cell line: U937 cells, None) , ( RNA: RXR-alpha mRNA, 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: RXR-alpha, None) , ( cell line: U937 cells, None) , ( RNA: RXR-alpha mRNA, None) 