CXCL12 and triple-negative breast carcinoma: In triple-negative breast cancer, the tumor subtypes rich in CAFs are more prone to bone metastasis, which is related to CXCL12 (C-X-C motif chemokine ligand 12) and IGF1 (insulin-like growth factor-1) cytokines and the CCL4-CCR5 (C-C motif chemokine ligand 4-C-C motif chemokine receptor 5) axis [66, 67].