resulting in a denser or uneven rise." It's the same effect, unfortunately, as using too little leavening agent (which is one of many cake baking mistakes that can and should be avoided), and as ...

If you desire neat, perfectly level cake layers, you need to be arranging your pans in a very specific way in the oven.

This will result in an uneven rise and a tough cake. You can, however, substitute plain flour for self-raising by adding sufficient raising agents.