7575
Moreover, we found that the ectopic expression of Smad7 , but not Smad6 , inhibited the activin A -induced Smad2 phosphorylation in HS-72 cells .
 ( cell line: HS-72 cells, None) , ( protein: Smad6, None) , ( protein: Smad7, 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:
 ( cell line: HS-72 cells, None) , ( protein: Smad6, None) , ( protein: Smad7, None) 