Signal transduction pathways are used to transfer information by biochemical means between different parts (in the spatial, topological and biochemical senses) of a living cell. How does the structure of a pathway determine the processing of the information? Is this processing unique to each given pathway variety? What are the constraints imposed on the information processing? I will address these questions using the examples of the NF-kappaB and MAPK pathways, discussing in detail the signaling events and the corresponding outcomes reflected in gene expression profiles.