Mission West Properties (MSW), a real estate investment trust that operates more than 100 research and development properties in Silicon Valley, is in talks to be acquired by a private equity fund for about $1.8 billion. The company's largest tenants include Microsoft Corp. (MSFT), Apple (AAPL) and NEC Electronics America. Mission West manages 107 properties totaling about 7.7 million rentable square feet. If the deal goes through, it would be the largest commercial property sale in Silicon Valley history, as measured by square footage. Mission West announced the negotiations in a press release Saturday, but did not name the potential acquirer. But media reports identify the bidder as Starwood Capital Group, a Connecticut-based real estate investment firm.