In a collagen type II mouse experimental arthritis model, Cry1−/−Cry2−/− mice displayed aggravated pathological changes in the arthritis disease score and increased serum levels of IL-1β, IL-6, MMP-3, and TNF-α as well as c-FOS and Wee-1 protein levels in spleen, markers also upregulated in human arthritis. Here, MMP3 is linked to arthritic joint disease.