MMP9 and breast cancer: For example, transfection of MCF-10A breast cancer cells with either c-erbB-2 or c-ras resulted in increased expression of MMP-2 (Giunciuglio et al, 1995), whereas transfection of MCF-7 cells with the ets gene PEA-3 led to increased production of MMP-9 (Kaya et al, 1996).