13665
p53 and p21/Cip1 , respectively, inhibit the expression and activation of PCNA , whereas p130 and pRb , respectively, inhibit the expression and activation of E2F1 .
 ( protein: pRb, None) , ( protein: PCNA, None) , ( protein: p21/Cip1, None) , ( protein: p53, None) , ( protein: p130, None) , ( protein: E2F1, 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: pRb, None) , ( protein: PCNA, None) , ( protein: p21/Cip1, None) , ( protein: p53, None) , ( protein: p130, None) , ( protein: E2F1, None) 