Epidermal Growth Factor (EGF) is a type of mitogenic factor that stimulates the proliferation of various cells, including epithelial cells and fibroblasts. It is a small peptide composed of 53 amino acids with a molecular weight of approximately 6,000 Daltons. EGF contains three disulfide bonds, which contribute to its stability under acidic and high-temperature conditions. Human EGF is synthesized as transmembrane precursor proteins (1207 amino acids), which are proteolytically cleaved to generate the 54 amino acid mature EGF. EGF plays a crucial role in regulating cell growth, proliferation, and differentiation. When EGF binds to its receptor (EGFR), it activates intracellular signaling pathways that lead to DNA synthesis and cell proliferation. EGF is naturally present in various tissues and body fluids, including saliva, urine, and milk. It is primarily synthesized in the submandibular glands and duodenum.