Chemoattractive and adhesion molecules play important roles in the selective homing and retention of cancer cells in the bone marrow vasculature, such as stromal cell-derived factor-1 (SDF-1), a chemokine ligand that binds to CXC chemokine receptors 4 and 7 (CXCR4 and CXCR7). The gene discussed is CXCR4; the disease is cancer.