Insulin-Transferrin-Selenium (ITS) is a supplement commonly used in cell culture media to support the growth and maintenance of various cell types particularly, for low density attachment of many adherent cell types. It provides essential nutrients and growth factors that improve cell survival and proliferation. The three main components of the ITS supplement are: 1. Insulin: A hormone that helps and regulate glucose uptake by cells and stimulates cellular growth and metabolism. In cell culture, insulin promotes the uptake of glucose and amino acids, which are crucial for energy production and biosynthesis. 2. Transferrin: A glycoprotein responsible for binding and transporting iron into cells. Iron is essential for many cellular processes, including DNA synthesis and cellular respiration. In culture, transferrin provides a stable source of iron, which can enhance cell growth and development. 3. Selenium: A trace element that acts as a cofactor for various antioxidant enzymes, such as glutathione peroxidase. Selenium helps protect cells from oxidative damage, which is critical for maintaining cell viability and preventing stress in culture. Together, these three components help maintain the health and viability of cells in vitro, especially in serum-free or reduced-serum culture conditions. ITS is commonly used for culturing primary cells, stem cells, and other sensitive cell lines, where serum may not be ideal or desired. In many cases, the supplement is added at a 1x final concentration (after dilution from a 100x stock) to basal media such as DMEM or RPMI. It can support various cell types, including epithelial cells, fibroblasts, and hepatocytes, among others.