For example, stromal cell-derived factor-1 (SDF-1/CXCL12) released from fibroblasts promotes cancer cell proliferation through a specific receptor, CXCR4, in several types of malignancies, including breast cancer (Orimo et al, 2005) and pancreatic cancer (Koshiba et al, 2000; Marchesi et al, 2004). The gene discussed is CXCL12; the disease is breast cancer.