Over the years, the Turtles have appeared in numerous cross-overs with other independent comics characters such as Dave Sim's Cerebus, Erik Larsen's Savage Dragon, Bob Burden's Flaming Carrot and Stan Sakai's Usagi Yojimbo. In 2009 Peter Laird sold the Turtles franchise to Viacom, the parent company of Nickelodeon, and as a result Mirage Studios had to shut down. At WonderCon 2011, it was announced that IDW Publishing had secured the rights to publish a new series and reprint the older comics.