8448
At physiological concentrations, DG and GG were weakly estrogenic, and they activated human NK cells in nutritionally relevant concentrations in vitro, probably at a site different from IL-2 action .
 ( cell type: NK cells, None) , ( protein: IL-2, None) , ( cell type: human NK 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: NK cells, None) , ( protein: IL-2, None) , ( cell type: human NK cells, None) 