Cover legend: Selective inactivation of transcription factor Pax6 in the cortex at the onset of neurogenesis causes a region-specific increase and ectopic localization of layer 5 (labeled with Ctip2; red) and layer 6 (labeled with Tbr1; green) neurons and an almost complete absence of upper cortical layers. Massive progenitor accumulation at the corticostriatal border also occurs in the mutant brain. For more information, see the article by Tuoc et al. in this issue (pages 8335–8349).