(a–c) Expression of the Dpi peptide inhibits NSC proliferation and promotes neuronal differentiation, and this effect could be reversed by the miR-219 inhibitor, TuD-miR-219. Mouse embryonic NSCs were transduced with virus expressing the Dpi peptide or a control peptide (C), in the absence or presence of TuD-miR-219. The virus-transduced cells were labelled with a GFP reporter. Cell proliferation was determined by the percentage of GFP+BrdU+ cells (BrdU+GFP+/GFP+; b) and neuronal differentiation was determined by the percentage of GFP+Tuj1+ cells (Tuj1+GFP+/GFP+; c). n=7 (b); n=5 (c). ‘n' represents experimental repeats. (d–g) Expression of Dpi inhibited NSC proliferation (d,e), but promoted neuronal differentiation (f,g) in mouse brains. E13.5 mouse brains were electroporated in utero with vectors expressing: (1) a control peptide and RFP reporter (C); (2) Dpi peptide and RFP reporter (Dpi); (3) TuD-miR-219 plus control peptide and RFP reporter (TuD-miR-219+C); or (4) TuD-miR-219 plus Dpi and RFP reporter (TuD-miR-219+Dpi). The electroporated cells were labelled with RFP, proliferating cells were labelled with Ki67 (e) and neuronal cells were labelled with DCX (f). The percentage of RFP+Ki67+ cells (e) or RFP+ cells that migrated to the CP (g) out of total RFP+ cells is shown. n=3 mice per group for panels (e,g). *P<0.05, **P<0.01 and ***P<0.001 by Student's t-test for panels (b,c,e,g). Scale bar, 100 μm for panel (a); 50 μm for panel (d); and 200 μm for panel (f).