6980
A silent mutation in codon 10 of exon 1 , detected in ER-negative and ER-positive human breast cancer cell lines , in breast tumors and blood DNA from breast cancer patients , has been recognized as a polymorphic site .
 ( DNA: codon 10, None) , ( DNA: blood DNA, None) , ( DNA: polymorphic site, None) , ( DNA: exon 1, 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:
 ( DNA: codon 10, None) , ( DNA: blood DNA, None) , ( DNA: polymorphic site, None) , ( DNA: exon 1, None) 