VEGF-A, also known as VEGF (vascular endothelial growth factor), is the founding member of the family including VEGF (VEGF-A), VEGF-B, VEGF-C, VEGF-D, VEGF-E, and PIGF. Vascular endothelial growth factors (VEGFs) are a family of secreted polypeptides with a highly conserved receptor-binding cystine-knot structure similar to that of the platelet-derived growth factors.VEGF-A has important roles in mammalian vascular development and in diseases involving abnormal growth of blood vessels such as tumor-related angiogenesis.VEGF-A is produced by diverse cell types, including aortic vascular smooth muscle cells, keratinocytes, macrophages and many tumor cells. Oxygen tension is a key physiological regulator of VEGF-A gene expression.