This is particularly important in light of recent studies showing that the core protein of syndecan-1, even when added exogenously to cells, can activate αVβ3 and αVβ5 integrins.(24,25,42) Importantly, the αVβ3 integrin is expressed on the surfaces of osteoclasts,(43) and inhibitors of this integrin can block metastasis to bone and tumor-related osteolysis.(44,45) Thus it is compelling to speculate that the shed syndecan-1 activates the αVβ3 integrin on osteoclasts, thereby enhancing osteoclastogenesis. Here, SDC1 is linked to neoplasm.