SHH and cancer: In vertebrate embryogenesis, Sonic Hedgehog (Shh) — one of the three members of the Hh protein family (Shh, Indian Hh (Ihh), and Desert Hh) — acts at significant distances from its source during development [1–4], maintains the stem cell niche, including the cancer stem cell niche [5], and progresses various cancers in the adult [5–7].