1574
RNAase protection assays demonstrated that the MMP9 activity, unique to infected cells , is due to increased MMP9 mRNA levels .
 ( protein: MMP9, None) , ( protein: MMP9, None) , ( cell type: infected cells, None) , ( protein: RNAase, 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: MMP9, None) , ( protein: MMP9, None) , ( cell type: infected cells, None) , ( protein: RNAase, None) 