A Zipcar parking sign in Cambridge has an increasingly ironic message. (Photo: Kim F.)

While Cambridge has been worrying about its biotechs, Boston’s Innovation District looks to have stolen away one of its bricks-and-mortar companies: Zipcar, the car-rental program.

The Boston Globe says the company has signed a letter of intent to move from its 25 First St. campus, with Zipcar’s chief executive, Scott Griffith, saying, “We’re looking forward to the prospect of making Boston’s Innovation District the home of our world headquarters in 2013. The Innovation District will provide Zipcar with exactly the atmosphere we are looking for to attract and retain a great pool of talent.”

Zipcar reports 496 employees and 400,000 members in the United States and United Kingdom. At the close of business Thursday, Zipcar’s stock was at $8.08 per share, down 14 cents. The 52-week high was $22 per share.

More details are here.

Meanwhile, the biotech Ironwood Pharmaceuticals has received FDA approval for an irritable bowel syndrome drug called Linzess, prompting a hiring surge of some 150 and 200 sales staff — but its chief executive, Peter Hecht, tells the Boston Business Journal that (in the words of writer Julie M. Donnelly) “the company has no immediate plans to move from its headquarters in Cambridge to the Boston Seaport, or anywhere else.”

“We’re happy where we are, and our employees are doing great here,” Hecht told the Journal. “Long-term we will need additional space, but we have not signed any agreement to move.”

Ironwood, at 301 Binney St., has 276 employees. It closed at $12.42 a share, down 24 cents, well between a 52-week range of $9.97 and $15.92 a share.

More details are here.