Medical and pharmaceutical giant Schering-Plough, which acquired local firm Organon BioSciences in November 2007, is offering all of Organon’s 33,000 square feet of lab space at 245 First St. in Cambridge for sublease, Banker & Tradesman has learned.

Organon’s lease on the vacated space expires at the end of February 2012, according to Boston-based tenant brokerage CresaPartners.

The building is part of the Equity Office portfolio purchased by private equity giant Blackstone for $39 billion in 2007. Significant chunks of sublease space in the building have become available in recent months, including 18,035 square feet from CombinatoRx, and 25,000 square feet from ViaCell, a firm that was purchased by Waltham-based PerkinElmer in November 2007.

A Schering-Plough spokesman said the former Organon employees would complete their transfer to Schering’s building at 320 Bent St. in Cambridge by the end of March.

More than 221,000 square feet of lab and office sublease space has come on-line in Cambridge since October.