VASH1 is a angiogenesis inhibitor. It inhibits migration, proliferation and network formation by endothelial cells as well as angiogenesis. This inhibitory effect is selective to endothelial cells as it does not affect the migration of smooth muscle cells or fibroblasts. It does not affect the proliferation of cancer cells in vitro, but inhibits tumor growth and tumor angiogenesis and acts in an autocrine manner. VASH1 also inhibits artery neointimal formation and macrophage infiltration and exhibits heparin-binding activity. There are two named isoforms.