TNFSF11 and breast cancer: To assess for alterations in osteoclast formation, RAW 264.7 pre-osteoclasts were tri-cultured with A) MDA-MB-231 human triple negative breast cancer cells (i) plus naïve osteoblasts (control) or (ii) plus EO-231 cells; or with B) MCF-7 human ER+ breast cancer cells (i) plus naïve osteoblasts (control) or (ii) plus EO-MCF-7 cells all in the presence of exogenous RANKL for six days (Figure 4a).