FGF is used to promote both stem cells and cell lines in culture. It is typically used in the concentration of 10-20 μg/mL. aFGF is active in many areas, and has many functions. It is known to participate in cell proliferation, differentiation, and migration in vitro. It binds to heparin, which potentiates its biological activity and protects it from proteolysis. rHu aFGF expressed in E. coli consists of a single, non-glycosylated, polypeptide chain that contains 141 amino acids and has a molecular mass of 15.97 kDa.