In addition, stromal cell-derived factor (SDF-1) also known as C-X-C motif chemokine 12 (CXCL12), secreted by stromal fibroblasts binds its cognate receptor CXCR4 on epithelial cells to trigger several downstream pathways involved in cell proliferation, cancer cell invasion and tumor angiogenesis [3–5]. The gene discussed is CXCL12; the disease is cancer.