The triggering of the CXCR4/CXCL12 signaling pathway enhances trans-endothelial migration and the homing and adhesion of cancer cells in the BM niche; it also increases the expression and excretion of other disease-progressing molecules (i.e., IL-6, integrins, and growth factors) [48,49]. This evidence concerns the gene CXCR4 and cancer.