The timing of neurogenic division is indicative of the laminar identity of the newborn cortical neuron. Neurons born in the dorsal VZ migrate in an inside-out fashion starting around E12.5, first to deep cortical layers (in the order: layers VI, V, and IV) on successive days and finally to the upper layers (II/III) around E15.5 (Arlotta et al., 2005). While direct neurogenesis from RGs produces deep-layer neurons during early corticogenesis, indirect neurogenesis via production of IPs contributes most to the neurons in the upper layer (Pontious et al., 2007). Pax6 is a master regulator of dorsal telencephalic fate (Muzio et al., 2002; Schuurmans et al., 2004; Stoykova et al., 2000; Toresson et al., 2000; Yun et al., 2001), but also has a role in regulating the kinetics of progenitor cell division (Quinn et al., 2007); in particular, Pax6-null mice display a specific thinning of the upper cortical layers due to premature asymmetrical cell division of the progenitors (Estivill-Torrus et al., 2002). BAF has been shown to interact with Pax6 to regulate the decision between direct and indirect neurogenesis (Tuoc et
