Figure 4. Y₁R deficiency inhibits the expression of essential bone-resorbing factors.

The proteolytic activity of MMP-9 in Y₁R^−/− osteoclasts was slightly diminished, as determined by gelatin zymography (A,B). In agreement, the mRNA expression levels of MMP-9 and CSTK were also downregulated in Y₁R^−/− cultures (C), which resulted in a trend towards decreased levels of released CTX-I (D). Data is expressed as mean ± SEM. **p < 0.01, ***p < 0.001 different from WT.