13609
To elucidate the role of retinoic acid (RA) in anti- CD40 + interleukin-4 ( IL-4 )-mediated B-cell activation , the effect of 10(-12) to 10(-6) mol/L RA was studied in anti-CD40 (1 microgram/mL) + IL-4 (5 ng/mL)-mediated proliferation and Ig synthesis by human peripheral blood mononuclear cells ( PBMC ) and B cells in healthy donors .
 ( protein: anti-CD40, None) , ( cell type: PBMC, None) , ( protein: IL-4, None) , ( protein: anti- CD40, None) , ( protein: IL-4, None) , ( protein: CD40, None) , ( cell type: B cells, None) , ( cell type: human peripheral blood mononuclear cells, None) , ( protein: interleukin-4, 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: anti-CD40, None) , ( cell type: PBMC, None) , ( protein: IL-4, None) , ( protein: anti- CD40, None) , ( protein: IL-4, None) , ( protein: CD40, None) , ( cell type: B cells, None) , ( cell type: human peripheral blood mononuclear cells, None) , ( protein: interleukin-4, None) 