Thus it forms an auto-positive feedback loop that enhances Shh signaling outcomes.5, 18 Although Gli1 is not essential for development, it is a potent oncogene and is required for Shh-induced tumor growth.19, 20, 21 Gli1 expression is elevated in many cancer types with elevated Shh signaling.3 Inhibiting Gli1 activity would likely be an effective approach for treating these cancers. Here, SHH is linked to neoplasm.