Fig. 5. msx1 fusion proteins and its phenotypic effects. (A) The constructs used to produce the Msx genes fusion proteins are represented in this figure. HD, msx homeodomain. GR, ligand binding domain of glucocorticoid receptor. See Materials and methods for details. (B) Embryos were injected with 700 pg of the indicated constructs, treated with dexamethasone immediately after the injection and the phenotype was analyzed at the tadpole stage. Anterior is towards the right. Top embryo, uninjected control; middle embryo, embryos injected with msx-GR. Note the inhibition of the anterior structures and ventralization of the embryo, similar to the effect of injection Msx genes mRNA (not shown). Bottom embryo, embryo injected with HDmsx-GR (dominant negative). Note that the effect, dorsalization, is similar to the injection of dominant negatives of msx1 (not shown).