A Wnt-class signaling pathway in Drosophila development. The Wnt signal is secreted from one cell and interacts with a receptor on another cell. The signal in this case results in gene activation, via a pathway that uses a receptor (Frizzled) and signaling proteins Dsh, Zw3, and β-catenin. The secreted Hedgehog protein also works through a signaling pathway, involving a different receptor and different set of signaling proteins, as shown. Cubitus interruptus is a zinc finger transcription factor involved in Hedgehog signaling; Smoothened is a membrane receptor for Hedgehog; and Patched is a protein that regulates the expression and function of Smoothened.