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NM23 was identified in a system of murine melanoma cell lines , in which an inverse relationship was found between NM23 expression and metastatic ability .
 ( protein: NM23, None) , ( protein: NM23, None) , ( cell line: murine melanoma cell lines, 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: NM23, None) , ( protein: NM23, None) , ( cell line: murine melanoma cell lines, None) 