Angiogenesis is important during development and in adult diseases, such as cancer, ischaemic heart disease and stroke. The generation of a complex vasculature is regulated by a number of signalling cascades and growth factors, including the bone morphogenetic protein (BMP) family. BMPs themselves are regulated by the modulators BMP endothelial cell precursor derived regulator (BMPER), chordin, noggin, gremlin/Drm and twisted gastrulation (Tsg). Jennifer Heinke and colleagues have previously shown that BMPER has a proangiogenic effect on endothelial cells, and in this work (p. 3082) they now analyse the functions of the other BMP modulators. Using a human umbilical vein endothelial cell (HUVEC) sprouting assay, they show that chordin and noggin have no stimulatory effect, whereas Tsg and gremlin enhance sprouting. Surprisingly, they found that both stimulation with Tsg and depletion of Tsg enhance the sprouting, migration and proliferation of HUVECs in a concentration-dependent manner, which results in activation of the AKT, ERK and SMAD signalling pathways that are known to be crucial for angiogenesis. Interestingly, when they stimulated HUVECs with BMPER and Tsg, endothelial sprouting was inhibited, suggesting that a tight balance between these factors in vivo results in their overall proangiogenic function. This notion is supported by their finding that, in zebrafish, both BMPER and Tsg are required for the normal development of the vasculature.