TGF-beta signalling pathways in early Xenopus development

Many different ligands of the TGF-beta superfamily signal in the early Xeno pus embryo and are required for the specification and patterning of the thr ee germ layers as well as for gastrulation. Recent advances in the field ar e helping us understand how ligand activity is regulated both spatially and temporally, the mechanism by which the signals are transduced to the nucle us and how essentially the same signalling pathway can activate completely different sets of genes in different regions of the embryo.