4744
ML-9 induced nitroblue tetrazolium ( NBT )-reducing activity of U937 cell more rapidly than VD3 : This differentiation marker was induced significantly after incubation with ML-9 and VD3 for 4 hours and 1 day, respectively.
 ( cell line: U937 cell, 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: U937 cell, None) 