And in the lab about 2% of the mouse cells that essentially are injected with this method will incorporate this DNA molecule into their cell genome. Now let's move on to method number two injection with viral agents. And the viral agents that are very effective are retroviruses. Why? Well, because retroviruses are these special viruses that contain reverse transcriptase and what this enzyme does is it essentially reverse transcribes the RNA molecule into the DNA molecule. And once we produce that viral double stranded DNA molecule in that cell that viral double strand DNA molecule is injected.