We have compared expression of involucrin, E-cadherin and P-cadherin in cultures of normal keratinocytes and in five different lines derived from squamous cell carcinomas (SCCs), using Northern analysis and immunofluorescence. In normal keratinocytes there was an inverse correlation between P-cadherin and involucrin expression, whereas E-cadherin was expressed by both basal and terminally differentiating cells. In SCC lines involucrin expression was lower than in normal keratinocytes, and there was variable expression of P- and E-cadherin: E-cadherin mRNA levels tended to be lower in SCC lines than in normal keratinocytes, whereas P-cadherin levels were similar. Our results are consistent with observations of cadherin expression in vivo and suggest that the cultures provide a useful experimental model for investigating the role of cadherins in determining the spatial organization of normal and neoplastic keratinocytes.