Demonstrates that orientation of the mitotic spindle and correct localization of proteins Numb and Prospero in Drosophila neuroblasts and epithelial cells in the procephalic neurogenic region require the inscuteable gene. Ectopic expression of inscuteable in other epithelial cells; Function of the inscuteable gene; Assymetric localization of the inscuteable gene; Localization of Numb and Prospero; Spindle orientation and reorientation; Discussion.