CTSK and neoplasm: Moreover, in Chemerin-treated media derived from metastatic breast cancer cells, an increase in the RANKL/OPG ratio and a reduction in the secretion of MMPs (e.g., MMP-2, MMP-9) and Cathepsin K were observed (148) (Table 1), thus inhibiting RANKL-induced OC formation and consequentially suppressing bone dissolution and tumor bone metastasis.