TIMP1 and osteoarthritis: Altered MMP/TIMP expression ratios have been associated with many diseases including: those associated with tissue destruction, such as cancer invasion and metastasis [16], rheumatoid arthritis [17], osteoarthritis [18]; those associated with fibrosis, such as liver cirrhosis [19], scleroderma [20], systemic sclerosis [21]; and those associated with weakening of the extracellular matrix, such as dilated cardiomyopathy and epidermolysis bullosa [12].