3170
A Western blot analysis was used to investigate HER-2/neu expression , whereas a chromium-release assay using the K562 cell line as target was used to measure natural killer (NK) cell activity .
 ( protein: HER-2/neu, None) , ( cell type: natural killer (NK) cell, None) , ( cell line: K562 cell line, 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: HER-2/neu, None) , ( cell type: natural killer (NK) cell, None) , ( cell line: K562 cell line, None) 