Abnormal differentiation patterns of UBR1−/−UBR2−/− neural precursors. Transverse sections of forebrain regions (boxed in A and B) in ED10.5 UBR1−/−UBR2−/− (B, D, F, H, J, and L) and UBR1+/+UBR2+/− control (A, C, E, G, I, and K) embryos were stained for DNA (blue), BrdU (red), pH3 (green), nestin (red), microtubule-associated protein 2 (MAP2) (green), tubulin-βIII (red), and/or GABA (green), as indicated above. (Scale bars: A and B, 200 μm; C–L, 40 μm.)