CXCL16 and breast cancer: Expression of CXCL16 can be also found in tumor-associated cells such as microglial and endothelial cells in glioblastoma multiforme [74], fibroblasts, endothelial cells, and macrophages in non-small cell lung cancer [76], mesenchymal stem cells (MSC) in gastric cancer [94,95], myeloid-derived suppressor cells (MDSC) in breast cancer [96], and cancer-associated fibroblasts (CAF) in breast cancer brain metastasis [97].