The 152LRSKSRSFQVSDEQY166 motif in the C-terminal fragment of MMP-3/7-cleaved mouse OPN, which corresponds to 167LRSKSKKFRRPDIQY181 in human OPN including different amino acids from mouse OPN, also binds to α9β1 integrin (Figure 2) and is involved in the occurrence of anti-type II collagen antibody-induced arthritis [60]. Here, SPP1 is linked to arthritic joint disease.