9204
Further optimization of culture conditions, type of Antigen Presenting Cells ( APC ), peptides , use of stabilizers like beta 2-m are still needed.
 ( cell type: APC, None) , ( protein: beta 2-m, None) , ( cell type: Antigen Presenting Cells, 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 type: APC, None) , ( protein: beta 2-m, None) , ( cell type: Antigen Presenting Cells, None) 