CXCR4 and breast carcinoma: Considering that similar results have also been reported in stem cells derived from canine mammary carcinoma, human hepatocellular carcinoma, or human glioblastoma, the CXCR4/CXCL12 axis could represent a promising target to overcome the problem of DR, and results obtained in veterinary oncology may represent a preclinical starting point for the future improvement of human therapeutic strategies.