1481
These benzidine-positive cells were positive for hemoglobin F staining .
 ( cell line: benzidine-positive cells, None) , ( protein: hemoglobin, 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:
 ( cell line: benzidine-positive cells, None) , ( protein: hemoglobin, None) 