MMP9 and breast carcinoma: In addition, the sera samples from breast cancer patients exhibited two other lytic activities of larger molecular size, similar to those previously identified as pro-MMP-9 dimers (200 kDa) and as a complex formed between pro-MMP-9 and its physiological inhibitor TIMP-1 (116 kDa) in colon cancer sera (Pucci-Minafra et al, 2001).