Explain distribution of dorsal after migration of nuclei.
Dorsal can either remain in the cytoplasm or migrate into the nucleus. The determination of whether it does this or not depends on Toll
if toll is present, it phosphorylates dorsal, releasing cactus from it, and allowing it to enter into the nucleus, where it will activate twist, a protein responsible for the ventral features of the nfruit fly.
If toll is absent, cactus remains bound, inhibiting it's entry into the nucleus and thus being unable to repress express ion of dpp, a gene responsible for the dorsal features of the fruit fly