And the other source of amino acids are the breakdown of preexisting proteins found inside our body, inside our cells. So recall that we ingest food, and then that food, if it contains protein, it makes its way into the lumen of the stomach. Now, in the lumen of the stomach, we have a low PH, a high acidity, an acidity of about two. So the PH is about two. And that low PH essentially stimulates it, activates an enzyme, a proteolytic enzyme known as pepsin. So the protein inside the stomach is essentially denatured.