Variable region: The antibody protein is Y-shaped consisting of amino acid chains. The stem and forking part of the Y-shaped antibody that is exactly the same in all antibody molecules within the same individual is called the constant region and the end of the Y-shaped molecule will vary widely between different antibodies, which is known as the variable region. Vascular endothelial growth factor (VEGF): A growth factor that is responsible for the growth of blood vessels. Vector: A plasmid or viral chromosome into whose genome a fragment of foreign DNA is inserted, and is used to carry the foreign DNA into a host cell. VEGF: Vascular endothelial growth factor, a growth factor that is responsible for the growth of blood vessels. Viral Vector: A virus that carries the gene to be introduced into a living cell by gene transfer technique. Most of the time the virus used as vectors are retroviruses. Before using them as vectors all the genes from most of the proteins are removed or altered except those necessary for transmission. The viral vectors are defective viruses and cannot multiply when they enter a cell. Vitiligo: This disorder is characterized by regions of otherwise normal skin of nonpigmented white patches of varied sizes, often symmetrically distributed and usually bordered by hyperpigmented areas. Hair in the affected areas is usually, but not always, white. Western Blotting: An electroblotting (the use of an electric field to transfer proteins or nucleic acids from the electrophoresis gel to the blotting membrane) method in which proteins are transferred from a gel to a thin, rigid support (nitrocellulose) and detected by binding of labeled antibody. Wild type: The form commonly found in nature.