Rob Bridgett tweets about the demise of his employer, saying: "RIP Radical Entertainment 1991-2012." Kotaku has a confirmation that while the developer of the Prototype series is not technically closed, it will no longer operate as a separate studio. Here's the statement they received from parent company Activision:

Although we made a substantial investment in the Prototype IP, it did not find a broad commercial audience. Radical is a very talented team of developers, however, we have explored various options for the studio, including a potential sale of the business, and have made a difficult conclusion through the consultation process that the only remaining option is a significant reduction in staff. As such, some employees will remain working for Radical Entertainment supporting other existing Activision Publishing projects, but the studio will cease development of its own games going forward.