631
The prostate-specific antigen ( PSA ) was downregulated to approximately 75% during the process.
 ( protein: prostate-specific antigen, None) , ( protein: PSA, 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: prostate-specific antigen, None) , ( protein: PSA, None) 