12391
First, a substantial number of cells can express class II molecules in the absence of CIITA , albeit at 5-fold reduced levels, most notably dendritic cells in s.c. lymph nodes; therefore, the CIITA gene cannot be an absolute ' master gene ' controlling the expression of class II molecules , as had been thought.
 ( DNA: CIITA gene, None) , ( protein: CIITA, None) , ( DNA: master gene, None) , ( cell type: dendritic cells, None) , ( protein: class II molecules, None) , ( protein: CIITA, None) , ( protein: class II molecules, 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: CIITA gene, None) , ( protein: CIITA, None) , ( DNA: master gene, None) , ( cell type: dendritic cells, None) , ( protein: class II molecules, None) , ( protein: CIITA, None) , ( protein: class II molecules, None) 