So SDS polyacrylamide gel electrophoresis apparatus, the proteins now begin to move as a result of that electric field in the perpendicular direction with respect to the direction in this case. So here we have along the x axis, and here we have movement along the y axis. So the x axis is perpendicular to the y axis, so they begin to move downward. This will separate the proteins that have identical pi values based on their different masses, different sizes. So we conclude that the two dimensional gel electrofreezes process is a highly effective method that separates the mixtures of the mixture proteins based on two different properties, so their isoelectric point and their size. So the horizontal direction is the isoelectric point.