Fig. 4. Cells expressing mature neuronal markers are very reduced in differentiated Sox2 mutant cultures. Neuronal markers in normal and mutant cells at differentiation day 9 (NeuN/β-tubulin, rows 1, 2; MAP2/β-tubulin, rows 3, 4; PSA-NCAM, row 5). Most β-tubulin-positive cells in normal are positive for mature markers NeuN or MAP2; by contrast, very few mutant cells are positive for these markers. Histograms show percentage of cells positive for NeuN/β-tubulin, rows 1, 2; MAP2/β-tubulin, rows 3, 4; PSA-NCAM, row 5, with wild-type average of 100%. Results from n=4 normal and n=4 mutant mice (see Table S1 in the supplementary material).