Polysaccharide of moving animals. Cellulose and chitin are examples of structural polysaccharides. Cellulose is used in the cell walls of plants and other organisms, and is said to be the most abundant organic molecule on Earth. It has many uses such as a significant role in the paper and textile industries, and is used as a feedstock for the production of rayon (via the viscose process), cellulose acetate, celluloid, and nitrocellulose. Chitin has a similar structure, but has nitrogen-containing side branches, increasing its strength. It is found in arthropod exoskeletons and in the cell walls of some fungi. It also has
Natural killer cell NK cell activity. Most of our current knowledge is derived from investigations of mouse splenic and human peripheral blood NK cells. However, in recent years tissue-resident NK cell populations have been described. These specialized NK-cell subsets can play a role in organ homeostasis. For example, NK cells are enriched in the human liver with a specific phenotype and take part in the control of liver fibrosis. Cancer Terms Natural killer cell Natural killer cells, or NK cells, are a type of cytotoxic lymphocyte critical to the innate immune system. The role NK cells play is analogous to that of cytotoxic