The precision and reproducibility of cellular processes poses a challenge to nonequilibrium many-body physics and our understanding of the physical principles that control the emergent properties of biological systems. Despite great experimental and theoretical progress in understanding the molecular nature of particular cellular components, we lack a framework for understanding how the interactions between these stochastic nonlinear elements result in reliable building blocks of life and information transmission. In fruit fly development, proteins sequentially turn on genes, the expression states of which lay out the blueprint for the segments of the insect’s body. A challenge to biophysics and developmental biology is to understand how the correct genes are turned on at the correct location in space and at the correct time during development to precisely produce and coordinate the numerous cell types present in the adult organism. I propose to study the general problem of how the molecular building blocks of the cell (proteins, genes) interact and result in a functional system on the specific example of early gene expression in fruit fly development.Current genetic manipulations in fruit flies will allow for experimental validation of the proposed molecular networks. I will work closely with experimental geneticists and biophysicist to understand the coordinated spatio-temporal expression of genes during development and describe their interactions in a quantitative manner. My broad goal is to extract global physical principles for the complex cellular interactions.