In addition, MMP-1 and MMP-9 were shown to be overexpressed in brain-seeking breast cancer cells in comparison with bone-seeking variants [107], while expression of MMP-2 and MMP-9 was found to be upregulated in breast cancer cells treated with angiotensin II, probably contributing to the increased migration through brain endothelial cells [108]. Here, MMP1 is linked to breast cancer.