MMP8 and breast carcinoma: Transwell invasion assays were used to assess the involvement of MEC-derived MMP-8 in the cross-talk between MECs and breast cancer cells during early invasion through basement membrane, MDA-MB-231 or SUM159 breast cancer cells were seeded onto transwells coated with Matrigel and co-cultured with β6-1089 cells expressing MMP-8 WT, MMP-8 EA or empty vector control plated onto outer chamber for 24 hours (Fig. 4).