Preheat the oven to 400°. Lightly coat 12 2½" muffin cups with cooking spray or insert cupcake liners. In a large bowl, stir together the all-purpose flour, rye flour, oat bran, cornmeal, sugar, baking powder and salt until well combined. With a mixing spoon, make a well in the center.
In a small bowl, stir together the milk, oil and egg, then pour the mixture into the well of the dry ingredients. Stir until just combined.
Spoon the batter into the prepared muffin cups, filling them 2/3 full. Bake for 20 minutes or until a toothpick inserted in the center comes out clean. Let the muffins cool in the pan for 5 minutes, then turn them out onto a wire rack to cool. Makes 12 muffins.