MMP2 and multicentric osteolysis-nodulosis-arthropathy spectrum: While mice deficient in MMP2 exhibit relatively mild skeletal defects which result in reduced bone mineralization and joint erosion, mutations in human MMP2 and MMP14 cause the severe connective tissue syndromes known as MONA (Multicentric Osteolysis, subcutaneous Nodulosis, and Athropathia) and Winchester Syndrome, respectively [16,17,18,19].