SOST and rheumatoid arthritis: The regulatory effect of the Wnt/β-catenin signaling pathway on osteoblast and chondroblast metabolism has recently become a hot topic of research.[3] We are now aware that Dickkopf-1 (DKK1) and sclerostin (SOST) are both upstream inhibitors of the Wnt/β-catenin pathway, and that both can negatively influence bone mass.[4,5] Diarra et al[6] inhibited DKK1 expression in a mouse model of rheumatoid arthritis.