13006
To characterize further the function of the intracellular vitamin D receptor ( VDR ), we have developed stable transfectant variants of a vitamin D-responsive cell line ( U937 ) which express either decreased or increased numbers of VDR .
 ( protein: VDR, None) , ( cell line: vitamin D-responsive cell line, None) , ( protein: vitamin D receptor, None) , ( protein: VDR, None) , ( cell line: U937, None) , ( protein: intracellular vitamin D receptor, None) , ( cell line: stable transfectant variants, 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: VDR, None) , ( cell line: vitamin D-responsive cell line, None) , ( protein: vitamin D receptor, None) , ( protein: VDR, None) , ( cell line: U937, None) , ( protein: intracellular vitamin D receptor, None) , ( cell line: stable transfectant variants, None) 