As previous studies have reported an intrinsic requirement for CCR6 in migration and fundamental functions of dendritic cells [44, 45], our finding of the reduced infiltration of dendritic cells in mammary tumors may not be a facet of cancer development in MMTV-PyMT Ccr6−/− mice, but is an inherent property of dendritic cell migration at a slower rate after CCR6 deletion. Here, CCR6 is linked to breast cancer.