Figure 4

α-Difluoromethylornithine (DFMO) treatment decreases lung metastasis of MDA-MB-231 cells. MDA-MB-231 cells were injected into the tail vein of athymic mice. DFMO treatment (2% per orally) began either 7 days prior to (DFMO-7), or 7 days (DFMO+7) or 14 days (DMFO+14) after, tumor cell injection. Mice were killed either 4 weeks (Experiment 1) or 6 weeks post injection (Experiment 2). Lungs were removed and fixed in Bouin's fixative diluted 1:5 in neutral buffered formalin. Each lung was examined for the presence of surface metastases. (a) The incidence of mice with lung metastases was graphed as a percentage of the total number of mice (n = 10 for each group). (b) The average number of metastases per lung was graphed as a percentage of the control (n = 10 for each group). Experiment 1 (black) and Experiment 2 (small hatched) are graphed separately as well as combined (large hatched).