Developmental tumours, early differentiation and the transforming growth factor beta superfamily

Embryonal carcinoma and embryonic stem cells have been very useful models f or identifying some of the factors that regulate differentiation in early m ammalian development. Here, we present a brief history of their original is olation and characterization and of their later introduction into the Hubre cht Laboratory. We illustrate in a review their contribution to our current understanding of the function of transforming growth factor beta and ligan ds binding to the receptors of a related factor, activin, in development wi th some of our own work.