SHH and esophageal squamous cell carcinoma: SHH signaling events have been implicated in tumor cell proliferation and survival as well as is the molecular hallmark of different human tumor entities that include esophageal squamous cell carcinoma, basal cell carcinoma [38], subsets of medulloblastoma [39], prostate cancer [40], colon cancer [41], brain tumors [42], rhabdomyosarcoma [43], and breast cancer [44].