Thank you for the answer.
I know I could just try it, and in fact I did it, but still I considered important enough to request an official answer, since there are many examples that suggest one thing but the correct answer is different. I give you one example with NGUI:
If you have a child on a GameObject (without a UI Panel) and this chlid has a different layer that the parent, at first it seems the child keeps its layer, but at some moment, the sprite changes the layer to the one of the parent.
In this example, my experiment could suggest an incorrect answer. This is why I ask when I doubt.