A major goal in angiogenesis research has been to inhibit tumor angiogenesis and growth. One approach has been to block NRP expression. Both mouse knockouts and zebrafish knockdowns show that angiogenesis is NRP-dependent. NRP knockdown in zebrafish also affects motor neurons adversely. Because of the many steps involved in angiogenesis, there are numerous target possibilities. Blocking NRP expression is one approach; sequestering VEGF with a NRP B domain peptide is another. There are numerous other strategies for inhibiting tumor angiogenesis that are based on VEGF and NRPs. SEMA3F inhibits tumor growth and metastasis. One possible mechanism is that SEMA3F repels blood vessels and EC.