416
So called costimulatory signals , mediated by other cell surface interactions or soluble cytokines produced by antigen presenting cells , are also required for complete T cell activation .
 ( protein: soluble cytokines, 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:
 ( protein: soluble cytokines, None) , ( cell type: antigen presenting cells, None) 