α-Difluoromethylornithine (DFMO) decreases the incidence and size of bone metastases from MDA-MB-435 cells. Green fluorescent protein-labeled MDA-MB-435 cells were injected intracardially into athymic mice. DFMO (2% per orally in drinking water ad libitum) treatment began 7 days prior to injection and continued for 6 weeks post injection. Bone metastases were visualized using a fluorescence microscope. (a) Photographs of femurs from control (n = 10) and DFMO-treated (n = 10) mice show the presence and size of the bone metastases. (b) Incidence of metastasis was determined by counting the number of mice with green fluorescence in the femur regardless of size of the mass. Image analysis was used to quantify fluorescence in each bone. (c) The area of tumor in bone was quantified by comparing the total area of the femur with the area containing green fluorescence. (d) The percentage of bone occupied by the tumor was also determined.