CXCL12 and breast cancer: In BC, the interaction between the chemokine receptor CXCR4 with its ligand CXCL12 can activate multiple signaling pathways, such as PI3K/AKT, Src/ERK1-2, NF-kB, STATE-3 and cross talk between CXCR4 and NOTCH, Wnt and SHH networks [84].