MMP9 and breast cancer: The mean level of MMP-9:TIMP-1 measured by ELISA in the 465 breast cancer plasma samples was 3.63 ng/mL (0.11 – 14.77 ng/mL) and the mean level of MMP-9:TIMP-1 measured by PLA in the 465 breast cancer plasma samples was 0.35 nM (0.09 – 3.50 nM).