In our team, we are studying the developmental functions of two intercellular signaling cascades, Wnt and retinoic acid signaling, in three animal models located at key phylogenetic positions within the deuterostome phylum. Namely, we are working on sea urchin (Paracentrotus lividus), amphioxus (Branchiostoma lanceolatum) and lamprey (Petromyzon marinus), respectively, an ambulacrarian, an invertebrate chordate and an agnathan vertebrate. Taking advantage of these three animal models, we use comparative approaches to assess the evolution of Wnt and retinoic acid signaling functions and of their interactions during deuterostome development.