TNFSF11 and breast cancer: In vitro, the observation that the conditioned medium of ISO-treated osteoblasts stimulated the migration of breast cancer cells, and that the RANKL decoy receptor osteoprotegerin (OPG) could block it, supported a stimulatory effect of βAR activation on breast cancer cell migration, via the upregulation of RANKL expression by the host stromal compartment [141].