By contrast, other methods of studying angiogenesis often involve adding or inhibiting one or more angiogenic factors8–11; for example, Wafai et al. showed that treatment with basic FGF or VEGFB improves the vascular deficits caused by bilateral femoral artery ligation10, and Penafuerte et al. showed that antagonising TGFβ inhibits tumour angiogenesis10,12. Here, TGFB1 is linked to neoplasm.