In the previous study, Slug has been reported to have an antiapoptotic effect on leukaemia cells and breast carcinoma cells (Inukai et al, 1999; Hemavathy et al, 2000; Kajita et al, 2004) and is capable to down regulate several epithelial markers involved in cell–cell adhesion such as cytokeratin18, muc-1, desmoplakin, occludin, and claudin-1 (Cano et al, 2000; Guaita et al, 2002; Kajita et al, 2004; Martinez-Estrada et al, 2005). This evidence concerns the gene CLDN1 and breast carcinoma.