Allergens trigger the airway epithelium to secrete growth factors, i.e., transforming growth factor-beta (TGF-β) superfamily members, matrix metalloproteinases, and epidermal growth factor (EGF), ultimately causing mesenchymal cell status, airway thickening, subepithelial fibrosis, and collagen deposition in asthma (3). Here, EGF is linked to asthma.