The goal of this project is to learn now epithelial keratinization is controlled in cultured human oral and epidermal keratinocytes. Specific studies seek to learn: 1. how the synthesis of keratin is regulated druing the process of differentiation; 2. if changes in nuclear chromatin structure can be correlated with the loss of viability that accompanies differentiation; 3. the mechanism by which adenovirus replication is blocked in the basal layer of keratinocyte cultures; 4. if human papilloma virus can be propaged in cultured epidermal keratinocytes; 5. the dominace or recessivity of the differentiated functions of cultured keratinocytes using somatic cell hybridization.