MMP9 and breast cancer: In vivo, RES reduced primary tumor volume and significantly impeded BC metastasis to the lung in a mouse model; researchers also observed lower serum levels of MPO-DNA and NE-DNA complexes after treatment and lower levels of MMP-2, MMP-9, E-cadherin and pro-inflammatory cytokines (IL-1β, IL-6 and TNF-α) in the metastatic lung.