Foxg1 haploinsufficiency reduces the population of cortical intermediate progenitor cells: effect of increased p21 expression.

Foxg1 is a transcription factor that is critical for forebrain development. Foxg1(+/Cre) mice were used to test the hypotheses 1) that the subventricular zone (SZ) generates supragranular neurons, 2) that Foxg1-regulated activities define the output from the SZ, and 3) that Foxg1 is involved in the suppression of p21-initiated cell-cycle exit. Foxg1(+/Cre) mice have thinner neocortices than wild-type controls, specifically in the supragranular layers, as detected by Brn2 immunostaining.