CXCL12 and breast cancer: These results are particularly intriguing as it is known that in samples of breast cancer patients VEGF mRNA levels are correlated with CXCR4 mRNA levels, and that the CXCR4/CXCL12 signaling axis can induce angiogenesis and tumor progression by increasing expression of VEGF through the activation of PI3K/Akt pathway [54].