Molecular characterization of genes led to the insight,
that flies and mammals are much more similar as initially anticipated.
Principle mechanisms underlying cell signaling are used for the communication
of cells in different contexts. The molecular control of eye development
may serve as a prominent example. Also within the one organism, the same
gene is often reused. Notch for example functions in at least six
different processes in Drosophila development and is conserved
between worms, flies, frogs and mice. The study of these signaling cascades
therefore has a broad implication.