Signal transduction in keratinocyte proliferation and differentiation

Keratinocytes, a key cellular component for both homeostasis and pathology of the skin, secrete a number of growth factors and cytokines, and their proliferation and differentiation are stimulated by a variety of biological factors. The major mechanism by which keratinocytes respond to extracellular signals is change in protein phosphorylation. In this review, we focus on factors known to influence keratinocyte proliferation and differentiation, such as epidermal growth factor family, nerve growth factor, transforming growth factor-β, insulin-like growth factor-1, keratinocyte growth factor, hepatocyte growth factor, cytokines. A hypothesis for a dual role of epidermal growth factor in keratinocyte proliferation and differentiation is proposed.Biomedical Reviews 1997; 8: 73-85