Figure 1

VEGF isoform patterning and its effects on vascular patterning. VEGF is patterned in tissues in an isoform-dependent manner, with loss of heparin binding affinity translating to less localized, broader distributions [12, 13]. A, Isoform specificity of VEGF distribution in the developing mouse hindbrain for mice transfected to express VEGF₁₂₀ versus wildtype mice, which express predominantly VEGF₁₆₄ [94]. B, Differences in VEGF localization are thought to give rise to vascular phenotypes that vary with the VEGF isoform, in a monotonic fashion. Larger isoforms, i.e. greater heparin binding affinity, give rise to sprouts that have greater filopodial directionality and vessels with greater branching density and smaller diameters. Similarly for VEGF proteolysis (red text): in tumors, loss of proteolysis exhibits similar features as VEGF₁₈₈-secreting tumors, while VEGF₁₂₀-secreting tumors have similar features as tumors secreting precleaved VEGF [6, 7].