MMP-9 is not required for endochondral fracture healing.

<p>A) Both MMP-9 deficient and WT littermates possessed abundant soft cartilage at 7 and 10 dpf. At 21 dpf, hard tissue callus dominated in MMP-9 deficient and WT littermates. B) Quantification of the total callus volume and % soft tissue fracture callus demonstrated that there was no significant difference between MMP-9 deficient mice and WT littermates at any time assessed. While the % soft tissue callus area appears to trend higher in MMP-9 deficient mice at 14 DPI as previously described [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0198088#pone.0198088.ref005" target="_blank">5</a>], there is marked variability between MMP-9 deficient mice.