Developers of some of Greater Boston largest projects are showing interest in becoming the master developer for Union Square and Boynton Yards. Mayor Joseph Curtatone’s office said in a press release last week that the city has received 10 responses to a request for qualifications released by the Somerville Redevelopment Authority in December to find partners to develop what could be more than 2 million square feet in the Union Square area. The MBTA’s Green Line Extension project will include a new station in the square that is expected to open by late 2016 or early 2017, and the city has identified a number of parcels in the area that could be redeveloped into new commercial, residential, and retail space. Among the developers that responded to the Redevelopment Authority are The HYM Investment Group, The Fallon Company, and a partnership of National Development and Federal Realty Investment Trust. The Redevelopment Authority, a civic advisory committee, and city staff will now work to identify finalists that will be asked to submit proposals for final evaluations.