6884
HIV-1 reactivation in resting peripheral blood mononuclear cells of infected adults upon in vitro CD4 cross-linking by ligands of the CDR2-loop in extracellular domain 1 .
 ( protein: CDR2-loop, None) , ( cell type: resting peripheral blood mononuclear cells, None) , ( protein: CD4, None) , ( protein: extracellular domain 1, 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: CDR2-loop, None) , ( cell type: resting peripheral blood mononuclear cells, None) , ( protein: CD4, None) , ( protein: extracellular domain 1, None) 