VEGF-C promotes tumor metastasis by inducing lymphangiogenesis. This study demonstrates that VEGF-C, when expressed in pancreatic β-cells, leads to the formation of extensive lymphatic networks around islets of Langerhans. When combined with a transgenic model of β-cell tumors that do not metastasize, the resulting double-transgenic mice develop tumors surrounded by well-developed lymphatics, with tumor cells frequently present in these lymphatics. These mice frequently develop pancreatic lymph node metastases, indicating that VEGF-C-induced lymphangiogenesis facilitates tumor cell dissemination and lymph node metastasis. The study shows that VEGF-C promotes lymphangiogenesis in the pancreas, which is not present in wild-type mice. The findings suggest that VEGF-C plays a direct role in tumor metastasis by enabling the formation of lymphatic pathways that allow tumor cells to spread to regional lymph nodes. The study also highlights the importance of VEGF-C in lymphatic development and its potential role in cancer progression. The results provide a model to study the mechanisms of lymphangiogenesis and lymphatic tumor metastasis, and to test potential inhibitors of these processes.VEGF-C promotes tumor metastasis by inducing lymphangiogenesis. This study demonstrates that VEGF-C, when expressed in pancreatic β-cells, leads to the formation of extensive lymphatic networks around islets of Langerhans. When combined with a transgenic model of β-cell tumors that do not metastasize, the resulting double-transgenic mice develop tumors surrounded by well-developed lymphatics, with tumor cells frequently present in these lymphatics. These mice frequently develop pancreatic lymph node metastases, indicating that VEGF-C-induced lymphangiogenesis facilitates tumor cell dissemination and lymph node metastasis. The study shows that VEGF-C promotes lymphangiogenesis in the pancreas, which is not present in wild-type mice. The findings suggest that VEGF-C plays a direct role in tumor metastasis by enabling the formation of lymphatic pathways that allow tumor cells to spread to regional lymph nodes. The study also highlights the importance of VEGF-C in lymphatic development and its potential role in cancer progression. The results provide a model to study the mechanisms of lymphangiogenesis and lymphatic tumor metastasis, and to test potential inhibitors of these processes.