MMP9 and cancer: We previously evaluated the effect of H2O2 or H2O2 + HA on 4T1 cancer cells and demonstrated that treatment of 4T1 cells with concentrations higher than 100 μM of H2O2 or 200 μM of H2O2 + HA leads to decreased survival, increased apoptosis, cell cycle disturbance, and decreased expression of MMP2, MMP9, and VEGF genes [26].