Fig. 4. Retroviral expression of Gsh2 represses Nkx2.1 expression in the MGE. Gsh2-expressing retroviruses were delivered to the developing telencephalon at E9.5 and analyzed at E14.5. Expression of bi-cistronic retroviral inserts was assayed by PLAP reporter expression. (A,D) Retrovirally infected, PLAP-expressing cells (red) are shown in the MGE (arrows) in coronal sections. (B,E) Nkx2.1 expression (green) in the MGE is repressed in clusters of retroviral expression. (C,F) Overlay of PLAP and Nkx2.1 shows a direct correspondence between retrovirally infected cells (red) and repression of Nkx2.1 expression (green). Scale bar in A: 25 µm (A-F).