MMP9 and osteoarthritis: Complexes containing proMMP9, NGAL, and TIMP1 have been demonstrated in the medium from cultured human neutrophils [12], MMP9/NGAL complexes—in the synovial fluid of patients with osteoarthritis [13], MMP9/TIMP1 complexes—in the urine of patients with prostate and bladder carcinoma [14], whereas MMP9/NGAL complexes—in the medium from human cholangiocarcinoma cell cultures [15].