Bmp signalling is crucial for patterning of the dorsal neural tube,inducing the formation of neural crest and roof-plate cells, and, later,promoting the differentiation of the dorsal spinal cord interneurons. On p. 1017, Liu et al. provide clues as to how Bmp signalling mediates this diverse range of activities. Msx genes, which encode homeodomain transcription factors, are often expressed in regions where Bmp signalling is active. The authors found that Msx1 overexpression in the chick neural tube represses neuronal differentiation, induces apoptosis and promotes roof-plate cell fate -mimicking the effect of constitutive Bmp signalling during early stages of neural tube development. By contrast, Msx3 overexpression imitates the effect of constitutive Bmp signalling during later stages, inducing interneuron cell fates. The authors suggest that Msx1 and Msx3 are downstream effectors of Bmp signalling during patterning of the dorsal neural tube, each mediating a subset of stage-dependent Bmp activities.