Acute inactivation of the conditional Stk25 allele by Cre causes a neuronal migration anomaly. A) The electroporation of GFP-encoding DNA into the developing cortex of E14.5 embryos marks neurons that have entered the upper portion of the cortical plate (CP) by E17.5. B) In contrast, Stk25fl/fl neurons that express GFP-Cre fail to populate the cortical plate and instead many are located in the intermediate zone. GFP-Cre-expressing neurons in the Stk25fl/+ mice migrate in a fashion similar to wild-type GFP-expressing neurons. C) Quantification of the GFP-expressing neurons in the indicated regions of the neocortex demonstrates that Stk25fl/fl neurons exposed to Cre (4) are statistically more likely to be in the intermediate (IZ) or subventricular (SVZ) zones and less likely to be in the cortical plate than Stk25fl/+; Cre-GFP (3), Stk25−/−; GFP (2) or wild-type; GFP (1) neurons (*P = 0.001, **P <0.0001 ANOVA with Tukey-Kramer post-hoc test).