Insulin-transferrin-selenite (ITS) can significantly reduce the demand of culture cells for fetal bovine serum(FBS) by supplementing these important common nutrients.

When the concentration of FBS is below 4%, either ITS or ITS-E can promote the growth of various adherent cells. It has been shown that the three supplemental ingredients can be utilized by most mammalian cells. They can promote cell proliferation and reduce the demand for serum by various cells.During cell culture with 2%-4% FSB, the supplementation with ITS or ITS-E into the medium can achieve a similar proliferation rate as in 10% FBS.

1. As a polypeptide hormone, insulin has multiple metabolic (catabolic) effects on mammalian cells, promoting glucose and amino acid uptake, fat production, monovalent cation and phosphate transport, and protein and nucleic acid synthesis.

2. As a carrier of iron, transferrin can also help reduce the toxic levels of oxygen free radicals and hydrogen peroxide.

3. Selenite is a cofactor of glutathione peroxidase and other proteins and is used as an antioxidant in culture media.

4. Ethanolamine plays an important role in the proliferation of mammalian cells and it is a precursor of phosphoethanolamine, the head group of a type of phospholipids important for plasma membrane synthesis.

ITS is recommended for the supplementation of RPMI-1640 and Earle's culture media.