Elevated levels of ADAMTS-12 in OA and RA, and ADAMTS-7 in RA were detected in the same tissues in which products generated by the cleavage of COMP were identified suggesting that COMP and these enzymes may co-localize (Liu et al., 2006a; Liu et al., 2006b; Luan et al., 2008; Lin and Liu, 2009). Here, ADAMTS12 is linked to rheumatoid arthritis.