MMP9 and breast cancer: There are five major classes of MMPs depending on their function and the substrates that they digest, including matrilysins (MMP-7 and MMP-26), collagenases (MMP-1, MMP-8, and MMP-13), stromelysins (MMP-3, MMP-10, and MMP-11), gelatinase (MMP-2 and MMP-9), and membrane-associated metalloproteinases (MMP-14, MMP-15, MMP-16, MMP-17, MMP-23A/B, MMP-24, and MMP-25) (18, 19). A retrospective SEER study on 25,323 women presenting with stage IV BC explored that 26.8% and 12.8% had overall survival of 5 and 10 years, respectively (20, 21).