The ΔNp63 protein, a product of the TP63 gene that lacks the N-terminal domain, 
has a critical role in the maintenance of self renewal and progenitor capacity 
in several types of epithelial tissues. ΔNp63 is frequently overexpressed in 
squamous cell carcinoma (SCC) and in some other epithelial tumours. This 
overexpression may contribute to tumour progression through dominant-negative 
effects on the transcriptionally active (TA) isoforms of the p53 family (TAp63, 
TAp73 and p53), as well as through independent mechanisms. However, the 
molecular basis of ΔNp63 overexpression is not fully understood. Here, we show 
that the expression of ΔNp63 is regulated by the Wnt/β-catenin pathway in human 
hepatocellular carcinoma (HCC) and SCC cell lines. This regulation operates in 
particular through TCF/LEF sites present in the P2 promoter of TP63. In 
addition, we show that ΔNp63 and β-catenin are frequently coexpressed and 
accumulated in oesophageal SCC, but not in HCC. These results suggest that 
activation of the β-catenin pathway may contribute to overexpression of ΔNp63 
during tumour progression, in a cell type-specific manner.