How broad are the conclusions that one can make from a heterologous expression experiment?
GSK3 is interesting because as a kinase, it is itself regulated by its phosphorylation status (particularly by Akt in neurons). Therefore, more protein does not necessarily mean more activity. For example from E13.5 to E15.5 GSK3 levels do not change but activity steadily increases. Hence if you increase GSK3 levels in neurons, it may not mean that downstream effects would change substantially, so I think although promising the in vivo effects may be hard to deduce from this experiment. If you see similar effects in in vitro neurons, you can be a bit more confident of potentially seeing similar effects with in utero electroporation in vivo