Indeed, certain xenografts that are resistant to anti-VEGF therapy are reported to be sensitive to anti-Dll4 (Noguera-Troise et al, 2006; Ridgway et al, 2006; Li et al, 2007), and combination treatment with anti-VEGF and anti-Dll4 has additive effects on tumour growth (Ridgway et al, 2006). Here, DLL4 is linked to neoplasm.