SOST and arthritic joint disease: Since, various agonists andantagonists, which are often secretory in nature -likesecreted frizzled-related protein (sFRP), sclerostin(SOST) and Dickkopf (DKK1)- tightly regulate WNTsignaling, it is possible that bone and cartilage modulateeach other via WNT signaling pathway and createpathological environment like arthritis.