Concentrations of TGF-β1 in tumor draining lymph nodes. A, TGF-β1 levels in tumor-draining lymph nodes (TDLNs) and the contralateral nodes (non-TDNLs) in the same mice were assessed using an ELISA. Prior to inoculation, tumor cells were transfected with either TGF-β1 gene or empty vector (mock). Note that in mice inoculated with TGF-β1-transfectants, TGF-β1 levels were higher in TDLNs than non-TDNLs. TGF-β1 levels were also higher in TDLNs draining TGF-β1-expressing tumors than tumors not expressing TGF-β1. B, Serum TGF-β1 levels measured in the same mice as in panel A. Serum TGF-β1 levels did not differ among the groups. *P < 0.05. n = 5 in each group.