The activation of the Nodal pathway induces the transcription of many target genes including of its own, but at the same time, micro-RNAs and other proteins interfere with this positive feedback loop in a negative manner at different points of the pathway. This balance of activation and inhibition of the signal is necessary to achieve the precise location, concentration and duration of downstream target genes that have an important role early in development. This article will summarize the role of some of the components that participate positively and negatively in regulation the signaling pathway. Although all the major components of Nodal signaling are evolutionarily conserved in almost all vertebrates, the regulation of each component of the pathway sometimes varies according to the species.
