Figure 5 shows leptin significantly induced migration (Fig 5A-D) and proliferation of 4T1 cells in vitro (Fig 5E–F). Remarkably, these leptin effects were completely abrogated by inhibition of Notch signaling either with DAPT or CSL-siRNA. Furthermore, the leptin-induction of Notch proteins/activation paralleled the leptin-mediated induction of proliferation/migration of breast cancer cells. In contrast, DAPT alone and control-siRNA has no significant effects on basal or leptin-induced 4T1 cell migration or proliferation (see Figure 5A–F). This evidence concerns the gene LEP and breast cancer.