Activin Receptors, Type IIActivin ReceptorsActivinsInhibin-beta SubunitsActivin Receptors, Type IInhibinsFollistatinReceptors, Growth FactorMyostatinReceptors, Transforming Growth Factor betaSmad2 ProteinBone Morphogenetic Protein Receptors, Type ISignal TransductionBone Morphogenetic ProteinsTransforming Growth Factor betaMolecular Sequence DataAmino Acid SequenceProtein-Serine-Threonine KinasesTrans-ActivatorsReceptors, MitogenReceptors, Cell SurfaceProtein BindingDNA-Binding ProteinsReceptors, G-Protein-CoupledLigandsMembrane ProteinsCell LineProtein Structure, TertiaryCells, CulturedNerve Tissue ProteinsNodal ProteinFollicle Stimulating Hormone, beta SubunitGoosecoid ProteinFollistatin-Related ProteinsSmad3 ProteinSmad ProteinsRNA, MessengerXenopus ProteinsGonadotrophsGrowth SubstancesMesodermEmbryonic InductionSmad4 ProteinFollicle Stimulating HormoneGlycoproteinsCell DifferentiationBase SequenceGene Expression Regulation, DevelopmentalDioxolesXenopusBone Morphogenetic Protein 4Smad7 ProteinGene ExpressionProteinsFetal ProteinsSequence Homology, Amino AcidEmbryo, NonmammalianReverse Transcriptase Polymerase Chain Reaction