Fig. 5. Regulation of N signaling during asymmetric cell division. (A) The cell fate determinants Neur (blue) and Numb (pink) are unequally segregated during the asymmetric division of the sensory organ precursor cell (SOP or pI) in Drosophila and are inherited by the pIIb daughter cell. -Adaptin (green) binds to Numb and is enriched at the anterior cortex of the dividing pI cell. (B) In the pIIb cell, the interaction of Numb with -Adaptin has been proposed to promote clathrin-mediated endocytosis of either N and/or Sanpodo to endosomes (E). Neur binds Delta (Dl), ubiquitinates it and promotes its endocytosis in the pIIb cell. It is not known whether the endocytosis of Dl is AP2-dependent. The endocytosis of Dl in pIIb leads to the activation of N in the pIIa cell. A possible role of Wasp in endocytosis may be to promote Dl internalization.