In a large bowl, combine the flour, cornmeal, sugar, baking powder, baking soda and salt. Combine the egg, sour cream, milk and butter; stir into dry ingredients just until moistened.
Pour into a greased 8-in. square baking dish. Bake at 400 degrees F for 20-25 minutes or until a toothpick inserted near the center comes out clean. Serve warm.