(A-F) Neuronal cell death induced by Pals1 down regulation (A-C) is efficiently rescued by simultaneous downregulation of GSK-3β activity obtained by expression of a kinase-dead GSK-3β expression vector (D-F). (G-L) GSK-3β overexpression elicits only a minor effect on cell death in control cortical tissue, while when combined with Pals1 down-regulation exerts a dramatic increase in neuronal cell death (J-L). DNA constructs are electroporated in E13.5 mouse cortices and results analyzed 48hr later. C, F, I, L show merged images of CC3-positive (red, apoptotic cells) and GFP electroporated cells (green). (M) Quantification of the electroporated (GFP+, green) and apoptotic (CC3+, red) cells per field for each different condition analyzed in (A-L)(ANOVA; p<0.0001; n=3). (N) Percentage of CC3-positive apoptotic figures within the total electroporated GFP-positive each different condition analyzed (ANOVA; p<0.0001; n=3).