A spatial toggle switch drives boundary formation in development.

Herein we introduce a multicellular network motif that performs as a spatial toggle switch and explains how boundary formation can be faithfully accomplished in developmental processes. Importantly, we show that expression and activity patterns of proteins must be simultaneously characterized for a proper understanding and description of the underlying mechanism. Our in silico experiments, in agreement with in vivo results, evaluate different genetic backgrounds and shed light on the dynamics of boundary formation. In addition, we provide an estimation of relevant biological parameters and a robustness analysis.