Immunofluorescent staining of tumor tissues showed that Ki-67-positive lymphatic endothelial cells were increased in TβRIIiΔLEC mice (Fig. 5d, e), and the expression level of VEGF-C was significantly increased in the tumor tissue of TβRIIiΔLEC mice compared to the control mice (Fig. 5f). This evidence concerns the gene VEGFC and neoplasm.