Serum is the blood component that is obtained after coagulation and removal of cellular components. Besides serum proteins, it contains, e.g. growth factors, amino acids, and hormones. This complex mixture makes serum one of the most important supplements supporting the cells growth and proliferation for in vitro cell culture. Of special interest is the Fetal Bovine Serum (FBS). It is especially rich in growth factors and is particularly low in antibodies that may negatively influence the cell culture work. It supports most cell lines and undergoes strict quality controls. Fetal Bovine Serum Low Endotoxin is a selected FBS featuring an endotoxin level lower than 1 EU/ml. This makes it especially suitable for sensitive cells, primary cell culture, and hybridoma cloning.