Figure 43.2 Cytoplasmic Factors Set Up Signaling Cascades Cytoplasmic movement changes the distributions of critical developmental signals. In the frog fertilized egg, the interaction of the protein kinase, the GSK-3 inhibitor, and the protein β-catenin results in differential concentrations of β-catenin in blastomeres following cleavage thereby specifying the dorsal–ventral axis of the embryo.