CXCL12 and cancer: The tumor cells, breast cancer-associated macrophage (41), and cancer-associated fibroblasts (CAF) secrete chemokines such as MCP-1 or CCL2, CCL20 (MIP-3A) (42, 43), and CXCL12 (SDF-1) as chemo-attraction of CD4+ T cell during differentiation of Th-17 cell and even for the selective attraction of Th-17 cell infiltration and/or its migration into the site of the tumor microenvironment (28).