4064
In situ hybridizations of adult murine tissues demonstrate Spi-B mRNA in the medulla of the thymus , the white pulp of the spleen , and the germinal centers of lymph nodes .
 ( RNA: Spi-B mRNA, None) , ( protein: Spi-B, 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:
 ( RNA: Spi-B mRNA, None) , ( protein: Spi-B, None) 