Our understanding of the role of RUNX2 in osteoblasts and osteosarcoma cells where the gene is endogenously expressed [23-29], provides a biological framework for analyzing the regulation and regulatory roles of RUNX2 in non-osseous cancer cells (for example, breast) in which RUNX2 is ectopically expressed [8-17]. The gene discussed is RUNX2; the disease is bone cancer.