Keratin (genitive ') meaning "horn" originating from the Proto-Indo-European "*ḱer-" of the same meaning. It is composed of "horn like", i.e., kerato, to which the chemical suffix -in is appended. The Greek ' is used in many animal names, e.g. "Rhinoceros", meaning "nose with a horn". Keratin filaments are abundant in keratinocytes in the cornified layer of the epidermis; these are proteins which have undergone keratinization. In addition, keratin filaments are present in epithelial cells in general. For example, mouse thymic epithelial cells (TECs) are known to react with antibodies for keratin 5, keratin 8, and keratin 14. These antibodies are
Keratin about 10 µm across, with cores and coating, and may be arranged in up to 10 layers, also in plaques of variable shape. Adult hornets also use silk as a glue, as do spiders. Some infectious fungi, such as those that cause athlete's foot and ringworm (i.e. the dermatophytes), or "Batrachochytrium dendrobatidis" (Chytrid fungus), feed on keratin. Diseases caused by mutations in the keratin genes include: Keratin expression is helpful in determining epithelial origin in anaplastic cancers. Tumors that express keratin include carcinomas, thymomas, sarcomas and trophoblastic neoplasms. Furthermore, the precise expression pattern of keratin subtypes allows prediction of the