Fan Casting Who should be the voices Casey Jones and Shredder in Seth Rogen's TMNT?

The cast was announced for Seth Rogen's TMNT animated movie, with voice actors such as Nicolas Cantu and Brady Noon, and big-name actors such as Jackie Chan, John Cena and Paul Rudd. However, characters such as Casey Jones and Shredder were for some reason absent. They might be hidden for the trailer on Monday, or they aren't in the film. Whatever the case may be, there is one question that we shall answer: Who should voice Casey Jones and Shredder?