Could proxy advisors sway investors to vote ‘no’ on BMS-Celgene merger?

Could proxy advisors sway investors to vote ‘no’ on BMS-Celgene merger?

Source: 
Fierce Pharma
snippet: 

Bristol-Myers and the activist investors at Starboard have had their say on the pending $74 billion Celgene merger. Some influential voices—namely proxy advisors—have yet to weigh in, though, and their verdicts could sway undecided shareholders ahead of the crucial April 12 vote.