LOS ANGELES (Reuters) – Roche Holding AG (ROG.VX), which last month acquired Genentech Inc, said on Tuesday that Arthur Levinson, the biotech company’s chief executive, would stay on as chair of a new Genentech board.

Levinson will no longer be CEO, but will be charged with steering integration of the two companies, serve as a scientific adviser and be nominated to the Roche board, the Swiss company said in a statement.

Roche has appointed several of its own executives to top non-research positions at Genentech as of May 1, including Pascal Soriot as CEO.

Roche said Susan Desmond-Hellmann, president of product development at Genentech, will hand over her responsibilities by mid-year, after which she will also act as an adviser to the company and join the scientific advisory board.

During the eight-month-long takeover battle that ended in March, Roche had said it expected Genentech senior management to stay on, but some shareholders and analysts have surmised that the biotech company’s prolific scientists and top managers would view the acquisition as an opportunity to leave.

Roche said Richard Scheller, executive vice president of Genentech research, will lead an independent research and development group within Roche, which will report directly to Chief Executive Severin Schwan.

Roche also said that William Burns, CEO of the Roche pharmaceutical group, will retire next January 1 and will also be nominated to the company’s board.

In addition, Marc Tessier-Lavigne, currently executive vice president of Genentech research drug discovery, will succeed Scheller as head of research and be appointed as Genentech’s chief scientific officer.

On the commercial side, Roche said Soriot, currently responsible for operations of the pharmaceutical division at Roche, will be appointed as CEO of Genentech, where he will lead all pharma activities in the United States.

Ian Clark, head of commercial operations at Genentech, will take over as head of global marketing and chief marketing officer for Roche’s entire pharmaceutical division.

Pat Yang will continue as head of technical operations at Genentech, while Hal Barron, currently head of Genentech development and chief medical officer, will become head of global development for oncology, immunology/tissue growth repair and virology.

Roche said David Ebersman, Genentech’s chief financial officer, and Steve Juelsgaard, chief compliance officer, will be leaving the company.

(Reporting by Deena Beasley, editing by Matthew Lewis and Tim Dobbyn, Gary Hill)