Shown is the mouse primary somatosensory cortex (S1) receiving axon projections (cyan) from cortical regions in the opposite brain hemisphere via the corpus callosum. These intracortical connections are important for neurodevelopment, but genetic determinants for axon targeting of distinct neuron populations were unclear until now. The transcription factor Mef2c is critical for the axonal targeting of Layer 2/3 neurons. Loss of Mef2c in Layer 2/3 neurons leads to EphA6 upregulation, which sensitizes axons to a repulsive EphrinA5 cue expressed by neurons in their homotopic target domain (magenta). See the article by Sriram Sudarsanam et al. for more information on the roles of Mef2c in cortical development. Cover image: Luis Guzman-Clavel.