CXCL12 and lung adenocarcinoma: Although CD8+ and Foxp3−CD4+ T cells can also express CXCR4, there are reports that CXCL12 preferentially attracts Tregs to human lung adenocarcinomas (62) and advanced cervical cancers (63), thereby indicating that targeting the CXCR4–CXCL12 axis may represent a useful means of selectively reducing the intra-tumoral Treg infiltrate.