Figure 4A) Microinjected cells in the VZ (magenta) of control (Con) and EPZ treated slices 24 h after microinjection and slice culture. Left: daughter cell pair in control section with asymmetric GFP expression, with cell 1 (basal location) being mild GFP-positive, and cell 2 (apical location) GFP-negative. Right: EPZ treated section showing a daughter cell pair with symmetric mild GFP-positive expression. Scale bars: 5 µm. Dotted shapes indicate the contour of Dx-A555 cell soma. B) Graph showing proportion of labelled cells expressing GFP-positive, -mild positive, or -negative, expressed as percentage of total cells per condition. Data information: Quantifications are based on three independent experiments (n=3, biological replicates) and Chi-square test was performed in all cases. Error bars represent SEM, ***p<0.001, ****p<0.0001, alpha = 0.05. VZ - ventricular zone. The following number of cells were scored: B) TIS21-GFP - 267 total cells were quantified (Con: 86 cells, EPZ: 181 cells).C) Symmetry or asymmetry in daughter cells' apical contact (yes/yes: both cells have apical contact; yes/no: one cell has apical contact and the other not; no/no: both cells lack apical contact). D) Symmetry (pos/pos, neg/neg) or asymmetry (pos/neg) in GFP expression in daughter cells expressed as percentage of total cells per condition. E) Symmetry or asymmetry in TUBB3 expression in daughter cells plotted (pos/pos: both cells express TUBB3; pos/neg: one cell expresses TUBB3 and the other not; neg/neg: none of the cells expresses TUBB3). Data information: Quantifications are based on three independent experiments (n=3, biological replicates) and Chi-square test was performed in all cases. Error bars represent SEM, ***p<0.001, ****p<0.0001, alpha = 0.05. The following number of cells were scored: C) Apical contact - 85 total daughter cell pairs (Con: 31 pairs, EPZ: 54 pairs). D) TIS21-GFP - 58 total daughter cell pairs (Con: 21 pairs, EPZ: 37 pairs). E) TUBB3 - 50 total daughter cell pairs (Con: 17 pairs, EPZ: 33 pairs).F) Phalloidin staining of control and EPZ treated sections showing cells during mitosis. Scale bar: 5 µm. G) Pie chart showing the proportion of cells with different angles of the cleavage plane in respect to the ventricular surface, divided in groups with increments of 30° . H) Percentage of cells undergoing symmetric or asymmetric cell division, defined by the cleavage plane bypassing or bysecting the apical plasma membrane, in control and EPZ treated samples. Data information: Quantifications are based on three independent experiments (n=3, biological replicates) and Chi-square test was performed in all cases. Error bars represent SEM, ***p<0.001, ****p<0.0001, alpha = 0.05. VZ - ventricular zone. The following number of cells were scored: G) For control condition 41 cells from four independent samples, 5 sections and 15 different images were assessed. EPZ treated quantifications were performed on a total of 26 cells from 3 independent samples, 5 sections and 16 images. H) For control condition a total of 37 cells from four independent samples, 5 sections and 15 different images were assessed. EPZ treated quantifications were performed on a total of 23 cells from 3 independent samples, 5 sections and 16 images.