Previous studies suggested that the VEGF-A/vascular endothelial growth factor receptor-2 (VEGFR-2) axis is the major pathway for angiogenesis [44], while the VEGF-C/VEGF-D/ vascular endothelial growth factor receptor-3 (VEGFR-3) axis is involved in lymphangiogenesis of cancer [45]. Here, FLT4 is linked to cancer.