The Foxn1 transgene may be contained in the germ and/or somatic cells; alternatively, the Foxn1 transgene may be contained only in a certain type of cell, such as epithelial cells, e.g., basal epithelial cells of the epidermis or hair follicles.Another aspect of the invention features an isolated nucleic acid sequence encoding a Foxn1 polypeptide, or a functional fragment or variant thereof, opera