CDH1 and neoplasm: Lacroix and Leclercq (2004) identified 72 differentially expressed genes between the (weakly) luminal epithelial and mesenchymal cell lines of which 15 genes (21%) coincide with differentially expressed genes in our ‘Epithelial’ vs ‘Fibroblastic’ cluster and are indicated in Tables 2, 3 and 4 with an asterisk. The finding that the three non-tumorigenic mammary cell lines derived from normal epithelium form a cluster close to the fibroblastic tumour cell lines is remarkable. However, given their fibroblastic morphology and the CDH1 promoter methylation, this is not unexpected.