Suprabasal-specific Cldns in epidermal tumor progression. Cldn6, Cldn11, Cldn12 and Cldn18 expression changes during epidermal tumorigenesis to occupy a gradually expanding zone of expression as observed after 2 (a-d), 6 (e-h) and 12 (i-l) weeks of the carcinogenesis protocol. While the localization of these suprabasal-specific Cldns shifted to varying degrees away from the cell membrane, there was a correspondingly varied reduction in the number of Cldn-positive epidermal cell layers in the lower strata of the epidermis after 6 and 12 weeks. The acetone-treated epidermis (after 12 weeks) is shown (m-p). A dotted line marks the base of the epidermal basal layer and the suprabasal zone is indicated with a bracket.