Immunostaining of Brain Samples

Immunostaining of brain sections or dissociated cells was performed as described previously^{26 (link),35 (link),64 (link)}. Primary antibodies used were mouse anti-ARID1B (Abcam, ab57461; Abnova, H00057492-M02), rabbit anti-cleaved caspase-3 (Cell Signaling Technology, #9664), mouse anti-BrdU (BD Biosciences, #555627), rabbit anti-p-histone-H3 (Cell Signaling Technology, #9701), rabbit anti-Ki67 (Cell Signaling, #9129), rabbit anti-β-catenin (Cell Signaling, #8480), chicken anti-GFP (Invitrogen, A10262), mouse anti-Parvalbumin (Sigma-Aldrich, MAB1572), rabbit anti-Cux1 (Sigma-Aldrich, SAB2105137), and rabbit anti-Tbr2 (Sigma-Aldrich, AB2283). Appropriate secondary antibodies conjugated with Alexa Fluor dyes (Invitrogen, A32731, A32727, A32723, A32732) were used to detect primary antibodies. DAPI (Sigma-Aldrich, D9542) was used to stain nuclei. No antigen retrieval was performed in this study.