These experiments were repeated using human MDA-MB-231 GFP/luc2 breast cancer cells (Figure S5), whereby we observed a 40% reduction in the number of TRAP-positive, multinucleated (≥3 nuclei) osteoclasts produced in the presence of EO-231 cells plus MDA-MB-231 GFP/luc2 breast cancer cells (Figure S5d). Here, ACP5 is linked to breast cancer.