Figure 12. A working model for Notch functions along the dv axis of Drosophila embryos.

Cells in the ventral region (including the mesectodermal cells at earlier stages) have the potential for canonical Notch signaling, which is blocked (e.g., in mesodermal cells) or realized (e.g., in neuroectodermal cells) in a stage-dependent manner. Most cells in the lateral regions (possibly excepting those that differentiate the peripheral nervous system) generate non-canonical Notch signaling at the cell surface. Factors that promote or suppress N^intra production or its nuclear transport might determine whether canonical or non-canonical Notch signaling predominates in a region.