The developer planning the proposed Atlantic Yards development in Brooklyn signed key documents Wednesday to allow the project to proceed.
A state agency has filed paperwork to force the sale of part of the 22-acre property through condemnation.
Opponents say they'll keep trying to stop the massive project, which is being built for the Nets and will cost $4.9 billion.
Last week, developer Forest City Ratner Cos. sold more than $500 million in bonds to finance the arena and completed a plan to sell 80 percent of the team and 45 percent of the arena to Russian billionaire Mikhail Prokhorov.