And what that means is they gained the ability to not only resist that particular drug that we were using, but also resist closely related drugs to that initial drug that we began with. And that is what we call multidrug resistance, the ability to resist many different types of drugs. Now, the question was what exactly allowed these cancer cells to actually gain multidrug resistance? Well, it turned out that the cancer cells began expressing a specific type of membrane protein within the membranes of those cancer cells. And what this membrane protein did was it used ATP to basically drive those molecules, the drugs, out of the cell. And it did that before the drugs could actually elicit their effects on the cancer cells.