Human Vascular Endothelial Growth Factor D (VEGF-D) is a member of the vascular endothelial growth factor (VEGF) family, which includes VEGF-A, VEGF-B, VEGF-C, VEGF-D, and placental growth factor (PlGF)—key regulators of angiogenesis and lymphangiogenesis. In humans, VEGF-D is produced by a variety of cell types including fibroblasts, macrophages, epithelial cells, and smooth muscle cells, particularly during development, inflammation, and tissue remodeling. VEGF-D is synthesized as a secreted precursor protein that undergoes proteolytic processing to generate a mature active form capable of binding primarily to VEGF receptor-3 (VEGFR-3/Flt-4) and also VEGF receptor-2 (VEGFR-2/KDR) on endothelial cells. Activation of these receptors stimulates intracellular signaling pathways such as MAPK/ERK and PI3K/AKT, promoting lymphatic endothelial cell proliferation, migration, and formation of lymphatic vessels, while also contributing to angiogenesis in certain tissues. In human physiology, VEGF-D plays important roles in lymphatic vessel development, fluid homeostasis, immune cell trafficking, and tissue repair. Dysregulated VEGF-D expression has been associated with tumor lymphangiogenesis and metastasis, as well as cardiovascular and pulmonary diseases, including lymphangioleiomyomatosis (LAM), where elevated circulating VEGF-D levels are used as a clinical diagnostic biomarker. Because of its role in regulating the lymphatic vasculature, human VEGF-D is widely studied in vascular biology, cancer research, and lymphatic disease, contributing to the development of therapeutic strategies targeting VEGF signaling pathways.