Introduction
Human epidermal growth factor (EGF) is a mitogenic growth factor that plays important roles in cell growth, proliferation, and differentiation. EGF is synthesized as a large precursor (1207 amino acids, 134 kDa) that is cleaved into a small mature protein (53 amino acids, 6 kDa). The precursor has 66% identity with the corresponding mouse protein (1, 3). Its gene mutation causes autosomal recessive renal hypomagnesemia (4). EGF binds to the cell surface receptor EGFR, leading to the phosphorylation of the receptor tyrosine kinase and subsequent activation of the signal transduction pathway. The EGFR inhibition by small molecule tyrosine kinase inhibitors and monoclonal antibodies is the target of non-small cell lung cancer, colorectal cancer, pancreatic cancer, and breast cancer therapies (5, 7).

Principle of the Assay
The AssayMax Human Epidermal Growth Factor (EGF) ELISA (Enzyme-Linked Immunosorbent Assay) kit is designed for detection of human EGF in urine, saliva, milk, and cell culture samples. This assay employs a quantitative sandwich enzyme immunoassay technique that measures human EGF in less than 5 hours. A polyclonal antibody specific for human EGF has been pre-coated onto a 96-well microplate with removable strips. EGF in standards and samples is sandwiched by the immobilized antibody and the biotinylated polyclonal antibody specific for EGF, which is recognized by a streptavidin-peroxidase conjugate. All unbound material is then washed away and a peroxidase enzyme substrate is added. The color development is stopped and the intensity of the color is measured.