450
From nuclear runoff experiments, we found that one subunit in particular, the B2 isoform (Mr = 56,000), was amplified primarily by transcriptional means .
 ( protein: B2 isoform, 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: B2 isoform, None) 