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 '
In the Shape of a Heart included two remixes. Browne is documented as saying that the song specifically addresses his relationship with his first wife, Phyllis Major, who died in March 1976 of a drug overdose: Jimmy Guterman, upon reviewing the album in 1986, singled out the song as a "mature version of the dark love songs on "The Pretender." With the lyric "I guess I never knew/What she was talking about" coupled with "I guess I never knew/What she was living without,'" Guterman writes, Browne "nails heartbreak to the wall and sends his listeners scurrying for the Kleenex." In 1989, the magazine referred to it