Targeted Expression of Activated ErbB-2 to the Epidermis of Transgenic Mice Elicits Striking Developmental Abnormalities in the Epidermis and Hair Follicles

The study investigated the role of the erbB-2 proto-oncogene in skin development by creating transgenic mice with an activated erbB-2 gene under the control of the human keratin 14 promoter. This targeted expression led to significant skin abnormalities, including epidermal hyperplasia, preneoplasia, and papilloma. Hair follicles were largely replaced by abnormal squamous structures, and the remaining follicles showed severe hyperplasia and disorganization. Most transgenic mice died before or shortly after birth due to skin and esophageal defects. These findings indicated that erbB-2 signaling played a crucial role in epidermal growth, differentiation, and hair follicle development.