The normal adult epidermis is a self renewing tissue consisting primarily of 10 to 20 layers in which cell proliferation is primarily restricted to the basal layer.The oral mucosa is a useful tissue to investigate the expression of differentiation linked molecules as it supports a broad range of epithelial differentiation within a relatively confined area. So an attractive approach to explore the molecular perturbation leading to an epidermal or an oral lesion is to investigate the expression of keratin genes in these lesions. Therefore a short review of keratin expression in normal epithelia...