2914
A 40-fold stimulation of chloramphenicol acetyltransferase activity mediated by four tandem repeats of the SNE could be induced within 2 h (and up to 250-fold within 6 h) after addition of TPA in DNA-transfected U-937 cells , indicating that the stimulation appeared likely to be a true protein kinase C -mediated signal transduction event rather than a differentiation response .
 ( DNA: SNE, None) , ( protein: protein kinase C, None) , ( DNA: tandem repeats, None) , ( cell line: U-937 cells, None) , ( cell line: DNA-transfected U-937 cells, None) , ( protein: chloramphenicol acetyltransferase, 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: SNE, None) , ( protein: protein kinase C, None) , ( DNA: tandem repeats, None) , ( cell line: U-937 cells, None) , ( cell line: DNA-transfected U-937 cells, None) , ( protein: chloramphenicol acetyltransferase, None) 