Su (fu) (for Suppressor-of-Fused) is a key negative regulator in the vertebrate Hedgehog signaling pathway. Su (fu) interacts with genes encoding proteins in this signal transduction pathway. In Drosophila, Intracellular transduction of the Hedgehog pathway involves the release of a large complex containing Su (fu). Su (fu) inhibits the activity of the transcription factor Gli1 and interacts with Gli2, Gli3 and the serine/threonine kinase Fused. Su (fu) is widely expressed in adult and embryonic tissues with higher expression in tissues patterned by hegdehog signaling. The Su (fu) gene locus maps to a region that is deleted in glioblastomas, prostate cancer, malignant melanoma and endometrial cancer.