Figure 1

Photodamaged skin shows diffuse Notch 1 expression in both basal and suprabasal epidermal layers (a). In solar keratosis, buds of atypical squamous cells with hyperchromic nuclei show loss of Notch 1 expression (b), while the basal cell layer is Notch 1 immunoreactive. Early UV-induced squamous cell carcinomas on sun-exposed site, characterized by detachment of individual, irregular aggregates of atypical squamous cells in the superficial dermis, downregulates Notch 1 protein expression (c) similarly to sheets and strands of squamous atypical epithelial cells, extending in the deep dermis, in clearly invasive UV-induced squamous cell carcinomas (d).