FIGURE 4. Restricted neural progenitors from the CNS and PNS proliferate normally in the absence of Bmi-1. E14 telencephalon cells or P0 or P30 SVZ cells were dissociated and cultured at clonal density under adherent conditions.

a–c, The frequency of CNS cells that formed neuron-only or glia-only colonies after 12–14 d in culture did not significantly differ between wild-type (WT) and Bmi-1^-/- mice (a), nor did the number of cells per neuron-only colony (b) or glia-only colony (c). d, The number of cells per glia-only colony formed by dissociated P0 gut cells did not differ between wild-type and Bmi-1^-/- mice. e, In BMP4-treated cultures of E14.5 gut p75⁺ cells, no difference was observed in the number of cells per neuron-only colony. f, Bmi-1^-/- neural progenitor colonies in the absence of Nrg proliferated at a significantly lower rate than did wild-type colonies (*P < 0.01), but Bmi-1^-/- colonies in the presence of Nrg proliferated similarly to wild-type colonies (although the difference was still statistically significant, *P < 0.05).