The activation of CXCL12 pathways may be involved in tumor progression and in the resistance to the conventional therapies both directly, promoting cancer cell proliferation/survival, invasion and cancer stem, and/or tumor-initiating cell phenotype, or indirectly, recruiting stromal cells to favor tumor relapse, metastasis, and angiogenesis [116–119]. The gene discussed is CXCL12; the disease is cancer.