So the PH value at which that particular protein basically has a net charge of zero. And after that, we expose that solution, that mixture of proteins, to the process of SDS polyacrylamide gel electrophoresis, also known as SDS Page. So P is the first letter. Then we have the A. Then we have the g then we have the E. So SD eight SDS page So isoelectric focusing can be combined with SDS polyacrylamide geelectrophrases, or SDS Page to create a more effective and more efficient way of purifying our crude mixture of proteins. And to see exactly what we mean, let's take a look at the following two steps.