This article reports that the specificity of a yeast cell's response to different environmental stimuli depends on the dynamics of nuclear translocation of a single transcription factor, Msn2. By artificially manipulating the amplitude, frequency and duration of Msn2 nuclear translocation and relating these parameters to the expression of an Msn2-dependent reporter gene in single cells, the authors developed a kinetic model that connects external inputs to differential gene expression via the dynamics of one signalling molecule.