8257
Unlike the proposed role of Cbl as a negative regulator, our results suggest that the Cbl homologue Cbl -b has a positive role in T-cell signaling , most likely via a direct interaction with the upstream kinase Zap-70 .
 ( protein: Cbl -b, None) , ( protein: upstream kinase, None) , ( protein: Cbl, None) , ( protein: Zap-70, None) , ( protein: Cbl, None) , ( protein: Cbl, 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: Cbl -b, None) , ( protein: upstream kinase, None) , ( protein: Cbl, None) , ( protein: Zap-70, None) , ( protein: Cbl, None) , ( protein: Cbl, None) 