Epidermal Growth Factor (EGF) is a growth factor that stimulates the prolife ion of epithelial and epidermal cells. EGF family members are characterized by three intramolecular disulfide bonds and can bind to four different receptor tyrosine kinases known as EGFR/ErbB1, ErbB2, ErbB3, and ErbB4. Recombinant EGF is a single, non-glycosylated Protein containing 53 amino acids, with a molecular weight of 6.2 kDa.