To explore the biological significance of leptin-Notch crosstalk in breast cancer, we addressed the question whether the reported induction of cell proliferation and migration by leptin is affected by inhibition of Notch activation (DAPT; a γ-secretase inhibitor) and/or down regulation of its DNA-binding partner (CSL gene knockdown using CSL-siRNA). This evidence concerns the gene RBPJ and breast carcinoma.