MMP9 and bone neoplasm: The results demonstrated that there were five targets (ACE, CXCR4, ELANE, MMP9, and MPO) mainly distributed in the bone marrow to regulate the proliferation, death, and apoptosis of bone cancer cells, and three targets (CYCS, MAPK3, and P2RX7) mainly distributed in the brain tissue may be related to the pain through regulation.