So, chief cells are also pretty easy to remember and that's because chief cells secrete a principal zymogen of the stomach known as Pipsinogen. So these cells, the chief cells release the principal or chief zymogen of the stomach, known as Pipsinogen. And once pepsinogen is actually released into our dust and it enters our aluminum of the stomach, if the PH is low enough, if the PH is around two, so if we have a very highly acidic environment, then our Pipsnogen will transform into the active form, the active enzyme known as pepsin. And pepsin is that protein, the enzyme, the proteolytic enzyme found in the stomach that is responsible for breaking down the protein into smaller polypeptides. And unlike these mucous cells, the chief cells are found lower within our duck region. So these purple cells are the cheap cells.