So our cells synthesize these zymogens we call procast spaces and these procast spaces undergo proteolytic activation to form their active form cast spaces. And the cast spaces are these enzymes responsible for activating the process of apatosis. And again we want to undergo aptosis in one of two instances if we have infested cells or if we want to stimulate the proper embryological development in that developing embryo. Now let's move on to five and six. So the most common type of fibrous protein that is found inside our body for example it's found in bone, it's found in skin and it's generally found in the areas surrounding our cells. So the extracellular environment, this fibrous protein as you might know is collagen.