And we'll see exactly what that means in just a moment. So if we obtain a positive test result to our essay, then what that means is that protein of interest is present in that sample. If we get a negative result, that means the protein is not present in that sample and we have to go out and get a new sample that does contain that protein. So whenever we're conducting some type of assay there are two questions we have to ask ourselves. Question number one is, is the protein present in our sample? And the way that we answer the question is by measuring the protein activity or if we're dealing with an enzyme, which is usually the case, we measure the enzyme activity of that protein and we'll see exactly how that's done in just a moment.