Figure 1. (A) Asymmetric segregation of cell fate determinants in asymmetric neuroblast cell division of Drosophila. Apical factors (such as Insecutable and Pins, and the evolutionary conserved Par complex consisting of Par-6, Bazooka, and Cdc42) shown in blue and basal factors (such as Miranda, Prospero, and Numb) shown in red are asymmetrically localized on the cortex along the apico–basal axis of neuroblast (left) and segregated asymmetrically to larger apical cell that retains neuroblast (NB) fate and smaller basal cell called ganglion mother cell (GMC). Mitotic spindle that orients along the apico–basal axis ensures asymmetric inheritance of the cortical cell fate determinants. Cdc2 activity is required to maintain the cortical asymmetry during cell division. (B) Asymmetric cell division of thoracic neuroblast 6-4 (NB6-4). NB6-4t divides asymmetrically to produce a neuroblast (blue) and gliablast (orange), whereas NB6-4a divides symmetrically giving rise to 2 glial cells. The neuroblast identity is maintained by high levels of Cyclin E (white stars), which is significantly reduced in NB6-4a.