As shown in Figure 3, both γ-irradiation as well as cyclophosphamide administration increase in BM expression of SDF-1, HGF/SF, S1P, and C1P, which on the one hand are potent chemotactic factors for tumor cells and, on the other hand, are potent pro-survival and anti-apoptotic agents for a variety of normal and malignant cells, including leukemia and lymphoma cells [3,17,80,81]. Here, CXCL12 is linked to leukemia.