We have previously shown that, in addition to its canonical role in invasion, MT1-MMP confers radio- and chemotherapy-resistance in breast cancer via ECM remodeling; and that inhibition of MT1-MMP sensitizes breast tumors to these therapies.11 Here we demonstrate that inhibition of MT1-MMP in patient derived GSCs is sufficient to inhibit invasion in vitro; and, importantly, MT1-MMP inhibition sensitizes GSCs to radiation, both in vitro and in vivo. The gene discussed is MMP14; the disease is breast carcinoma.