SP7 and rheumatoid arthritis: However, osteoblasts isolated from trabecular bone of RA patients cultured with adiponectin showed reduced mRNA expression of osteoblast differentiation marker osterix and increased osteoprotegerin (RANKL competitive inhibitor).94 Overall these data indicate that adiponectin contributes to bone damage in rheumatoid arthritis: where it directly reduces osteoblast differentiation, whilst stimulating osteoclastogenesis leading to enhanced bone resorption (Fig. 3B).