The Boston Herald speculates on casting for Disney’s upcoming Underdog, a live-action update to the popular ’60s animated series. Set to open in theaters on August 3, 2007, the film’s title character will be played by a real dog, provided with a computer generated mouth. Rumor has it that Nicolas Cage was offered to voice Underdog but declined the role. Hence, word now arrives that the two stars currently in running for the title part are none than other Steve Martin and Dane Cook. Jim Belushi is also linked to Underdog, though his role remains unknown at this time.