FLT4 and neoplasm: Extensive studies have showed that tumor- or stromal-secreted cytokines such as VEGF-C and VEGF-D, and their cognate receptor tyrosine kinase VEGFR-3 located on LECs are critical regulators of lymphangiogenesis, these molecules advance or regulate proliferation, migration, metastasis and survival of LECs, growth of new lymphatic capillaries and lymphatic tube formation in tumorigenesis, thus promote metastatic spread of tumor cells to lymph nodes [20, 28].