Interaction of Sox1, Sox2, Sox3 and Oct4 during primary neurogenesis

► Sox1, Sox2 and Sox3 inhibit BMP signaling and induce neural tissue. ► SoxB1 proteins are not redundant but rather induce unique gene expression profiles. ► Oct91, the Xenopus homologue of Oct4, behaves similarly to the SoxB1s. ► Constitutively active Sox1 and Sox2 repress neuron formation; Sox3 causes apoptosis. ► The synergy in mammals between Sox2 and Oct4 is conserved in frogs.