Components of signal transduction pathways have evolved as connected hubs, recognizing several binding partners with remarkable affinities and specificities. Ras is one of these hubs, sensitive to rapid and subtle changes, thus enabling the correct transfer of information. The dynamic nature of such systems makes their structural characterization challenging, despite the vast amount of experimental data available. These data, however, can be used as a restraint for generating comprehensive models of the association of Ras with its effectors. We believe that by following this type of approach, the derived 3D models can provide atomistic understanding of important biological issues, such as how Ras discriminates between the Ras binding domains of its various effectors. The modeled binding interfaces could be used as the starting points for selective modulations of interactions and pathways using small molecules, peptides or mutagenesis.