ALL cells are highly dependent on bone marrow stromal support for in vitro proliferation and survival [5], and bone marrow stroma can provide protection from the cytotoxic effects of chemotherapeutic agents [6], an effect at least partly mediated by chemokine (C-X-C motif) ligand 12 (CXCL12) [7]. The gene discussed is CXCL12; the disease is acute lymphoblastic leukemia.