The ability of the conditioned medium of IL-1β-treated MCF-7 cells to induce OC differentiation and activity through the bone resorption pit assay, despite its inability in the co-treatment with Bobcat339, indicated a potential involvement of epigenetic activity of IL-1β in the induction of the bone osteolytic mechanism of breast cancer. The gene discussed is IL1B; the disease is breast carcinoma.