The <i>CXCL12</i>/<i>CXCR4</i> axis also orchestrates interactions with the tumor microenvironment, facilitating chemotaxis toward <i>CXCL12</i>-rich niches (e.g., bone marrow and brain) and modulating anti-tumor immunity via regulatory cells. This evidence concerns the gene CXCR4 and neoplasm.