Matrix metalloproteinase-3 (MMP3) is well known as a secretory endopeptidase degrading extracellular matrices (ECM) and involved in many physiological and pathological processes.Recent reports indicated the presence of MMPs in the nucleus; however,its function has not been well investigated.On theother hand,we have shown that the second member of CCN family protein/connective tissue growth factor (CCN2/CTGF) plays an important role in development and regeneration of skeletal tissues such as cartilage and bone,especially through ECM production.