Now, what is a protein assay? Well, a protein assay is some type of test. It's some type of procedure that allows us to identify the presence of that specific protein of interest based on some type of specific property or some type of specific functionality of that protein. 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.