(A–B′) The expression of radial progenitor markers, RC2 and GLAST, is strongly reduced in E17.5 Mek1,2\Nes mutant radial progenitors (n=3). In A–A′, scale bar=100μm. In B–B′, scale bar=50 μm. (C–C′) Pax6 immunostaining of radial progenitor nuclei is not obviously different between E17.5 Mek1,2\Nes and WT cortices. Scale bar=100 μm. (D–D′) EGFP labeled radial progenitors at E18 after in utero electroporation of pCAG-EGFP into E16.5 Mek1,2\Nes and WT dorsal cortices. Radial progenitors in Mek1,2\Nes animals exhibited a normal morphological appearance. See also Figure S1.