4740
Reversible differentiation of human monoblastic leukemia U937 cells by ML-9 , an inhibitor of myosin light chain kinase .
 ( protein: myosin light chain kinase, None) , ( cell line: human monoblastic leukemia 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:
 ( protein: myosin light chain kinase, None) , ( cell line: human monoblastic leukemia U937 cells, None) 