{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,10]],"date-time":"2026-06-10T15:16:13Z","timestamp":1781104573951,"version":"3.54.1"},"reference-count":0,"publisher":"National Academy of Sciences","issue":"14","content-domain":{"domain":["www.pnas.org"],"crossmark-restriction":true},"short-container-title":["Proc. Natl. Acad. Sci. U.S.A."],"published-print":{"date-parts":[[1984,7]]},"abstract":"<jats:p>A number of recent studies have indicated that the expression of keratins is altered upon malignant transformation of human epithelial cells. We have shown that the altered expression of 67-kDa and 40-kDa keratins in established squamous cell carcinoma lines from tongue and epidermis stems largely from a difference in their sensitivity to vitamin A apparently acquired during tumorigenesis. When the vitamin A concentration in the medium is raised, the 40-kDa keratin is produced at increased levels. Conversely, when the amount of vitamin is reduced, the 67-kDa keratin is synthesized and the cells undergo stratification and terminal differentiation. However, even when vitamin A is quantitatively removed from the medium, the maximal degree of differentiation attained by each squamous cell carcinoma cell as judged by the synthesis of 67-kDa keratin was still less than that of the normal keratinocytes. These findings suggest that the altered patterns of keratins observed for some tissues upon malignant transformation arise from a complex mixture of intracellular changes in the differentiative pathway in addition to changes in the responsiveness of cells to extracellular regulators of keratin gene expression.<\/jats:p>","DOI":"10.1073\/pnas.81.14.4280","type":"journal-article","created":{"date-parts":[[2006,5,31]],"date-time":"2006-05-31T05:27:08Z","timestamp":1149053228000},"page":"4280-4284","update-policy":"https:\/\/doi.org\/10.1073\/pnas.cm10313","source":"Crossref","is-referenced-by-count":78,"title":["Differences in keratin synthesis between normal epithelial cells and squamous cell carcinomas are mediated by vitamin A."],"prefix":"10.1073","volume":"81","author":[{"given":"K H","family":"Kim","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"F","family":"Schwartz","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"E","family":"Fuchs","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"341","published-online":{"date-parts":[[1984,7]]},"container-title":["Proceedings of the National Academy of Sciences"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/pnas.org\/doi\/pdf\/10.1073\/pnas.81.14.4280","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2022,4,13]],"date-time":"2022-04-13T12:03:06Z","timestamp":1649851386000},"score":1,"resource":{"primary":{"URL":"https:\/\/pnas.org\/doi\/full\/10.1073\/pnas.81.14.4280"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[1984,7]]},"references-count":0,"journal-issue":{"issue":"14","published-print":{"date-parts":[[1984,7]]}},"alternative-id":["10.1073\/pnas.81.14.4280"],"URL":"https:\/\/doi.org\/10.1073\/pnas.81.14.4280","relation":{},"ISSN":["0027-8424","1091-6490"],"issn-type":[{"value":"0027-8424","type":"print"},{"value":"1091-6490","type":"electronic"}],"subject":[],"published":{"date-parts":[[1984,7]]},"assertion":[{"value":"1984-07-01","order":2,"name":"published","label":"Published","group":{"name":"publication_history","label":"Publication History"}}]}}