13335
The two Duffy polymorphic antigens , Fya and Fyb (coded by the FY*A and FY*B alleles ), are present on erythrocyte membranes .
 ( protein: erythrocyte membranes, None) , ( protein: Duffy polymorphic antigens, None) , ( protein: Fya, None) , ( protein: Fyb, 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: erythrocyte membranes, None) , ( protein: Duffy polymorphic antigens, None) , ( protein: Fya, None) , ( protein: Fyb, None) 