CXCR4 and alopecia areata: Although we did not further investigate the involvement of the CXCL12/CXCR4 pathway in the immune cell infiltration of AGA hair follicles, single-cell analysis in alopecia areata revealed that CXCR4 is highly expressed on immune cells, such as CD4+ T cells, CD8+ T cells, and dendritic cells, and is co-expressed with inflammatory cytokines and chemokines [8].