CXCR4 and breast cancer: Furthermore, these vesicles induced the upregulation of genes involved in breast cancer cell migration, such as C-X-C chemokine receptor type 4 (CXCR4) and vascular endothelial growth factor C. These vesicles also upregulated genes involved in metastasis, including tumor growth factor (TGF-b), basic fibroblast growth factor (bFGF), and epidermal growth factor (EGF).