The Hedgehog signaling pathway, a mediator of proliferation and differentiation in vertebrate embryogenesis, has been reported to be implicated in the development of several cancers including medulloblastoma, pancreatic cancer, gastric cancer, and breast cancer.18, 19, 20 There exist three types of Hedgehog homologs in the mammalian signaling pathway family, among which Sonic Hedgehog (SHH) is best investigated. The gene discussed is SHH; the disease is cancer.