RPMI (Roswell Park Memorial Institute) medium is a commonly used cell culture medium designed to support the growth of various mammalian cells, particularly immune cells like lymphocytes. It contains essential nutrients, such as amino acids, vitamins, glucose, and salts, and can be supplemented with fetal bovine serum (FBS) for optimal cell growth. RPMI is widely used in research, particularly in studies involving cancer, immunology, and hematology.