The cellular machinery is governed by interacting proteins, genes and metabolites that form complex and highly interconnected networks of interactions. This way, extracellular stimuli triggers pathways of biological events that regulate gene expression, protein activity, and ultimately, cell response. The architecture of these signaling cascades is highly nonlinear, integrating multiple layers and loops of feedback and feedforward regulation. These nonlinearities strongly affect the dynamics of activation and de-activation of the signaling cascades, inducing emerging properties such as bistability, oscillations or ultra-sensitivity. To understand cellular decisions, it is not sufficient to understand the function of each of the proteins in a pathway, and a deep understanding of the consequences of the nonlinear wiring of the pathway is required. We use in vivo experiments and theoretical approaches to understand how the wiring of the pathways affects the role of the proteins that regulate these decision, in the context of balance between proliferation and differentiation of stems cells during neurogenesis.