CK10 (Cytokeratin 10) is expressed in all suprabasal layers of the epidermis. In the epidermis, expression of CK10 strictly parallels the extent of differentiation; it is absent in the basal layer, appears in the first suprabasal layers and increases in concentration towards the granular layer. Expression of CK10 is related to maturation of malignant keratinocytes, being preferentially detected in more-differentiated parts.