Pre-heat your oven to 350° F, and add patriotic cupcake liners to muffin tins.
Add the cake mix, egg whites, buttermilk, and softened butter to a large bowl.
Mix everything together, 'til the batter is completely smooth.
Divide the batter into 3 small bowls (you should have about 1 1/4 cups of batter in each bowl; then add red coloring to one bowl of batter, and blue coloring to another bowl of batter, leaving one bowl with white batter.
Transfer the cake batter to disposable decorator bags* to make it easier to fill the cupcake liners.
Squeeze equal amounts of each color of batter into the cupcake liners.*
Bake the cupcakes at 350° F for about 12-14 minutes, or until a toothpick inserted in the center comes out clean. Then cool completely on a wire rack.