CXCR4 and breast cancer: In addition, these vesicles induced the upregulation of genes involved in breast cancer cell migration, such as C-X-C chemokine receptor type 4 (CXCR4) and VEGF-C, and those involved in metastasis, such as tumor growth factor β (TGF-β), basic fibroblast growth factor (bFGF), and epidermal growth factor (EGF).