And that's why this is called a two dimensional gel electrophoresis process, because we separate along the x axis, then along the y axis, and those are two different dimensions. So once we take this and place it into our electrophoresis setup, we see that what begins to happen is they begin to migrate down towards the positively charged end of this SDS Page setup. And so if any one of these bands consists of different proteins that have different mass values, that are different sizes, we're going to be able to separate them along the vertical direction based on their size. So in this case, we separate them based on their isoelectric point, but in this case, we separate them based on their mass, based on their size. So we see that this slab, this band, consists of at least four different proteins, because these four different proteins contain different size values, different masses. Likewise, the second band consists of at least two proteins, the third band consists of at least one, two, three proteins.