ITS-A (Insulin-Transferrin-Selenium-Sodium Pyruvate) Supplement is used as a basal medium supplement in order to reduce the amount of Fetal Bovine Serum (FBS) used to culture cells. ITS-A is used for adherent cell cultures. Originally used with RPMI 1640 and Minimum Essential Medium (MEM), ITS-A is now routinely used with other basal media to support a wide variety of cell types in the presence of 2–4% FBS.