1454
Furthermore, expression of OBF-1 in HeLa cells selectively stimulates the activity of a natural immunoglobulin promoter in an octamer site -dependent manner .
 ( DNA: immunoglobulin promoter, None) , ( protein: OBF-1, None) , ( DNA: octamer site, None) , ( cell line: HeLa 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:
 ( DNA: immunoglobulin promoter, None) , ( protein: OBF-1, None) , ( DNA: octamer site, None) , ( cell line: HeLa cells, None) 