We observed a 19% reduction in the number of TRAP-positive, multinucleated (≥3 nuclei) osteoclasts produced in the presence of EO-231 cells plus MDA-MB-231 breast cancer cells when compared to the number of TRAP-positive, multinucleated (≥3 nuclei) osteoclasts produced in the presence of naïve osteoblasts plus MDA-MB-231 breast cancer cells (Figure 4e). The gene discussed is ACP5; the disease is breast cancer.