The Boston Hearld -- The shake-up continues at Biogen Idec. A day after longtime CEO James Mullen retired, corporate raider and management critic Carl Icahn strengthened his foothold at the drug-making Cambridge firm. At yesterday’s annual shareholders meeting, Icahn pick Eric Rowinsky joined the board along with Biogen-backed Stephen Sherwin. Incumbents Nancy Leaming and Brian Posner were re-elected.
