13278
ER variants, generated by alternative splicing, have been detected in human breast cancer , but also in normal mammary glands , therefore their role in tumorigenesis has been questioned.
 ( protein: ER, 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: ER, None) 