Melt margarine over medium-high heat in a nonstick skillet coated with cooking spray. Saute corn and bell pepper for 8 minutes or until corn is lightly browned and bell pepper is tender; stir frequently. Cool.
Combine vegetable mixture, cornmeal mix, flour, sugar, and ground red pepper in a large bowl; add milk and egg whites, stirring until moist. Pour batter into a 9-inch round cake pan coated with cooking spray. Bake at 400° for 30 minutes or until a wooden pick inserted in center comes out clean. Remove from pan; cool completely on a wire rack.
Note: Substitute 1 1/3 cups plain yellow cornmeal, 2 teaspoons baking powder, and 1/2 teaspoon salt for 1 1/3 cups self-rising yellow cornmeal mix, if desired.