1919
In contrast, analysis of pp90rsk activity by phosphorylation of a peptide derived from S6 protein demonstrated stimulation of this kinase in TPA-treated U-937 , and not TUR , cells .
 ( protein: kinase, None) , ( protein: S6 protein, None) , ( protein: pp90rsk, 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: kinase, None) , ( protein: S6 protein, None) , ( protein: pp90rsk, None) 