Asymmetry and cell fate in the Drosophila embryonic CNS.

Drosophila CNS precursors, neuroblasts, repeatedly divide to produce a large neuroblast and a smaller GMC. This division is asymmetric with regard to sibling cell size, mitotic potential and gene expression. Recent work has identified a number of molecules that show a polarized distribution during neuroblast mitosis: prospero RNA and Inscuteable, Miranda, Prospero, Staufen, and Numb proteins. The process of asymmetric localization of proteins and RNAs is cell cycle dependent, microfilament dependent and coordinated with the positioning of the mitotic spindle, which results in the unequal distribution of cell fate determinants to a specific daughter cell at cytokinesis.