Embryonic development and morphogenesis of individual organs are common schemes based processes. In them, groups of undifferentiated cells, they initiate a series of complex interactions with internal and external signals, in order to establish patterns that direct cells to their subsequent proliferation, differentiation, coordinated morphological change and migration. This seemingly elementary, requires the integration of a series of activations and changes in the expression levels of a few basic genes. Two mechanisms are paramount in this general scheme: the proper control of temporal and spatial activation patterns of cell signaling, and the union of these patterns with cellular effectors that activate cellular responses in terms of gene activity or cell morphology. (more...)