Now, one example that we're going to look at in the next several electrodes is prothrombin. This is a very important zymogen that is activated into the thrombin which basically needed to produce those fibrin molecules that essentially form that clock. Now let's discuss three, four, five and six. So we have hormonal enzymes, we have a process known as apatosis or program cell death. We have a very important fibrous protein that is found in bone and skin. Basically, that is a component of the extracellular environment known as collagen.