CXCR4 and metastatic malignant neoplasm: In addition, it has been shown that C‐X‐C motif chemokine ligand 12 (CXCL12) signaling through the C‐X‐C chemokine receptor type 4 (CXCR4) receptor in cancer cells plays an important role in the retention and homing to bone of both cancers that develop in the bone marrow, as well as metastatic cancer cells.64, 65, 66 Osteocytes produce CXCL12 and therefore could activate the CXCL12‐CXCR4 signaling axis in cancer cells, favoring their homing to bone.67 However, alternatively it is also possible that osteocytes prevent the migration and arrival to bone of metastatic breast cancer cells.