1132
Human RAR alpha expression was unchanged in H9 and CEM cells , and elevated in U937 cells , after PMA stimulation.
 ( cell line: H9, None) , ( cell line: CEM cells, None) , ( cell line: U937 cells, 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 line: H9, None) , ( cell line: CEM cells, None) , ( cell line: U937 cells, None) 