12723
The class II transactivator ( CIITA ) is essential for the expression of major histocompatibility complex (MHC) class II antigens .
 ( protein: major histocompatibility complex (MHC) class II antigens, None) , ( protein: class II transactivator, None) , ( protein: CIITA, 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: major histocompatibility complex (MHC) class II antigens, None) , ( protein: class II transactivator, None) , ( protein: CIITA, None) 