Colorectal carcinomas are characterized by a heterogeneous differentiation pattern. Cancer cells in central regions are epithelially-differentiated, whereas disseminating tumour cells at the invasion front have undergone epithelial-mesenchymal transition and show nuclear accumulation of β-catenin. Nuclear β-catenin cooperates with transcriptional repressors of the E-cadherin gene to induce epithelial-mesenchymal transition and activates expression of target genes that drive malignant tumour progression.