To determine whether inhibition of Notch1 signaling affects NF-κB activity and MenaINV expression in vivo, as observed in vitro, we treated mice bearing either human breast cancer cell xenografts (MBA-MB-231 cells injected into the mammary fat pad) or PyMT [34] breast tumors with the γ-secretase inhibitor, DAPT, or control for two weeks (Fig. 5A and Additional file 9: Fig. S7A) [36]. This evidence concerns the gene NOTCH1 and breast cancer.