Hedgehog (Hh) proteins, important regulators of development, bind the cell-surface protein Patched, allowing activation of Smoothened. In vertebrates, this ultimately leads to the activation of the zinc-finger transcription factors of the Gli family. Overactivation of this pathway contributes to certain cancers, including glioblastoma, for which the Gli proteins are named. Hh antagonist VIII is a cell-permeable quinazolinyl-urea compound that has been shown to inhibit Gli transcription activity with an IC50 value of 70 nM.