Background: Vascular endothelial growth factors (VEGFs) are a family of closely related growth factors having a conserved pattern of eight cysteine residues and sharing common VEGF receptors. VEGFs stimulate endothelial cells, induce angiogenesis, promote cell migration, increase vascular permeability, and inhibit apoptosis. VEGFB has structural similarities to VEGF and PIGF and is frequently co-expressed with VEGF. There are two alternatively spliced isoforms of VEGFB: VEGFB 167 and VEGFB 186. VEGFB 167, a highly basic heparin-binding protein, remains with the cell or extracellular matrix whereas, VEGFB 186 is readily secreted. VEGFB stimulates endothelial cell proliferation. VEGFB binds to the tyrosine kinase receptor VEGFR1 (flt1) and does not bind to VEGFR2. Vascular Endothelial Growth Factor B is widely expressed but is most abundant in heart, skeletal muscle, and pancreas. It has been suggested that VEGFB expression in human primary breast cancers is associated with lymph node metastasis. The genes that encode VEGFB have been mapped to chromosome 11q13.