Remarkably, TWIST upregulation was reported in lobular breast cancer as an alternative for inactivating mutations of CDH1 (Yang et al, 2004) and, moreover, SUM44PE, the only breast cancer cell line of lobular origin in our panel, showed the highest expression of TWIST. As TWIST is not significantly differentially expressed in the fibroblastic cell lines, we suggest that its protein product has a direct effect on CDH1 and results in a similar phenotype as CDH1 mutations, thereby contributing to the typical phenotype of lobular breast cancer. The gene discussed is CDH1; the disease is Hereditary breast cancer.