Recombinant Human EGF is a 6.2 kDa globular protein containing 53 amino acid residues, including 3 intramolecular disulfide bonds. The ED50 was determined by a cell proliferation assay using balb/c 3T3 cells is ≤ 0.1 ng/ml, corresponding to a specific activity of ≥ 1 x 10^7 units/mg.