CXCR4 and neoplasm: nmTECs and tumor-associated fibroblasts preferentially expressed CXCL12, and thymic B cells and helper T cells, including TFH and Treg cells, expressed its receptor, CXCR4. Given that the CXCR4-CXCL12 axis has been shown to be important in T-cell homing in synovial tissues of rheumatoid arthritis43, neurogenesis44, and maintenance of hematopoietic stem cells45, the interaction may be important for nmTEC-mediated T-cell regulation (Fig. 5d).