Association of EGF receptor expression with proliferating cells and of ras p21 expression with differentiating cells in various skin tumours

The localization of DNA replicating cells, epidermal growth factor (EGF) receptor-expressing cells and ras oncogene product p21 (p-21(ras)) positive cells were examined in various skin tumours to elucidate the role of EGF receptor and p21(ras) in the epidermis. Normal skin, keratoacanthoma (KA), solar keratosis (SK), Bowen's disease (BD), squamous cell carcinoma (SCC), basal cell carcinoma (BCC) and extramammary Paget's disease (PD) were studied. EGF receptors were seen in proliferating layers, where DNA replicating cells localize, but p21(ras) was found in the more differentiated layers. We conclude that EGF receptor expression is closely associated with cellular proliferation, but p21(ras) may play a role in the differentiation of cells in various skin tumours.