ROLE OF INSCUTEABLE IN ORIENTING ASYMMETRIC CELL DIVISIONS IN DROSOPHILA

Drosophila neuroblasts and epithelial cells in the procephalic neuroge nic region divide perpendicular to the surface, and segregate the prot eins Numb and Prospero into the basal daughter cell. We demonstrate he re that orientation of the mitotic spindle and correct localization of Numb and Prospero in these cells require the inscuteable gone. Moreov er, ectopic expression of inscuteable in other epithelial cells leads to spindle reorientation. the Inscuteable protein localizes to the api cal cell cortex before mitosis, suggesting that Inscuteable functions in establishing polarity for asymmetric cell division.