Osteopontin was expressed in ~ 47% of cells in the bones of tumor-bearing mice injected with MDA-MB-231GFP/Luc2 cells plus EO-231 cells and expressed in ~ 80% of cells in the bones of tumor-bearing mice injected with MDA-MB-231GFP/Luc2 cells plus MC3T3-E1 cells (Fig. 3). The gene discussed is SPP1; the disease is neoplasm.