It is well established that excessive SPP1 and CXCL12 are associated with cancer angiogenesis, metastasis, and malignancy.74,75 In addition, excessive angiogenesis mediated by SPP1 and CXCL12 in the synovium may exacerbate joint destruction in RA patients. Here, CXCL12 is linked to rheumatoid arthritis.