Epithelial cells in vivo exist as confluent cell sheets, but this confluence is disrupted if the sheets are wounded, if the cells are undergoing morphogenesis, or if they are taking part in invasion and metastasis. Desmosomes are one of the principal types of adhesive junctions in epithelia and are responsible for maintaining tissue integrity. It is likely that modulation of desmosomal adhesion is required to facilitate cell motility in response to alterations in the tissue architecture. Desmosomal adhesion changes from a calcium-dependent state to a calcium-independent state when cells become confluent. Our laboratory has shown that the α isoform of protein kinase C is involved in signaling the response of desmosomes to calcium concentration and wounding, in cultured epithelial cells and in mouse epidermis (in vivo).
