5876
The B cell-associated surface molecule CD40 plays a key role in T cell-dependent B cell maturation , as individuals with defects in either CD40 or its ligand are impaired in immunoglobulin isotype class switching and germinal center formation .
 ( protein: CD40, None) , ( protein: B cell-associated surface molecule, None) , ( protein: CD40, None) , ( protein: immunoglobulin, 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: CD40, None) , ( protein: B cell-associated surface molecule, None) , ( protein: CD40, None) , ( protein: immunoglobulin, None) 