To address this issue we stimulated estrogen-dependent MCF7 breast cancer-derived cells and highly invasive, hormone-independent MDA-MB-231 breast cancer-derived cells with TNF-α and subsequently assessed changes in cell migration in conjunction with the levels of two dipeptidyl peptidases, FAP-α and CD26, and three metalloproteases, MT1-MMP, MMP2 and MMP9. Here, MMP9 is linked to breast cancer.