Tumor-derived TGF-β1 suppresses migration of immature DCs from tumors to TDLNs. A, To assess migration of DCs from tumors to TDLNs, cultured bone-marrow dendritic cells (bmDCs) were labeled with CFSE and injected into the tumors. Shown are numbers of CFSE-labeled bmDCs within TDLNs counted by flow cytometry 24 h after injection. B, To clarify the maturation status of the migrated bmDCs, untreated immature CFSE-labeled bmDCs and LPS-treated mature CFSE-labeled bmDCs were injected. Note that the numbers of immature bmDCs migrating from TGF-β1-transfected tumors was lower than from mock-transfected tumors, whereas there was no significant difference between the numbers of migrated mature bmDCs. n = 10 in each group. LPS, lipopolysaccharide.