Xsox17α and -β Mediate Endoderm Formation in Xenopus

Brivanlou and Melton, 1992; Kessler and Melton, 1994; Schulte-Merker et al., 1994). At a later stage, signals Clare Hudson, Debbie Clements, Rosalind V. Friday, David Stott, and Hugh R. Woodland* originating in the dorsal organizer region (e.g., noggin, Department of Biological Sciences chordin, and nodal-related molecules) and local signalUniversity of Warwick ing molecules in the ventral and lateral equatorial region Coventry CV4 7AL (BMP4, Xwnt8) pattern the dorsal–ventral axis (Lemaire, United Kingdom 1996; Lemaire and Kodjabachian, 1996). Some of these