SOST and neoplasm: It has been reported that peripheral blood and bone marrow plasma from multiple myeloma patients contain elevated levels of Sclerostin.17 Additionally, an anti-Sclerostin antibody was shown to increase bone mass without affecting the progression of the tumor.18 However, we observed herein that mature osteocyte-derived CM had a stronger tumor-suppressive capability than premature osteocyte-derived CM, and the results indicated a dichotomous role for Sclerostin as well as Lrp5 in osteocytes and tumor cells.