Now, other evidence also suggests that we have 16 proteases that are involved in bone remodeling as well as MHC class two processing. And remember, MHC class two is a protein complex found on certain cells, immune cells of our body where MHC stands for the major historic compatibility class two complex. Now, these cysteine proteases are also found in many other organisms and they are found predominantly in fruits. And so papaya type of fruit contains a special cysteine protease known as papain. Now let's move on to aspartyl or aspartate proteases as well as metallic proteases. So once again from the title, from that name you can infer that instead of having Serene or cysteine inside these active sites of these enzymes, we have aspartic acid.