Keratin Keratin Keratin () is one of a family of fibrous structural proteins. It is the key structural material making up hair, horns, claws, hooves, and the outer layer of human skin. Keratin is also the protein that protects epithelial cells from damage or stress. Keratin is extremely insoluble in water and organic solvents. Keratin monomers assemble into bundles to form intermediate filaments, which are tough and form strong unmineralized epidermal appendages found in reptiles, birds, amphibians, and mammals. The only other biological matter known to approximate the toughness of keratinized tissue is chitin. Keratin derives from Greek ' from '
The Keg of Nails is a replica of a keg used to ship nails. The exchange is believed to have been initiated by fraternity chapters on the UC and U of L campuses, signifying that the winning players in the game were "tough as nails." The present keg is actually a replacement for the original award, which was misplaced by Louisville, lost during some construction of office facilities. It is adorned with the logos of both schools and the scores of the series games. The rivalry went on hiatus following the 2013 season, as Louisville moved to the Atlantic Coast Conference on July 1,