CCN2 and systemic sclerosis: Moreover, we found that CD109 inhibits ECM (fibronectin and collagen type I) and CCN2 protein production in both SSc and normal skin fibroblasts - as evidenced by the findings that CD109 siRNA-transfected SSc and normal skin fibroblasts display elevated fibronectin, collagen type I and CCN2 protein levels, whereas treatment with a recombinant CD109 protein leads to a decrease in levels of these proteins.