Evidence for this comes from the exclusive production of the collagen and proteoglycan proteinase MMP-1 by chondrocytes in diseased joints, and from arthritis mouse models where an increased level of cartilage damage was seen when apoptosis of chondrocytes was prevented [Ainola et al., 2005; Barksby et al., 2006; Butler et al., 1997; Otero and Goldring, 2007]. Here, MMP1 is linked to arthritic joint disease.