Table 2.

Modes of signaling in Hedgehog (Hh) pathway-dependent cancer.

	Hh Signaling	Example of Cancers
Type I	Mutations on Ptch1, Smo, or suppressor of Fused (SUFU). Ligand independent cancers with autonomous Hh signaling	Nevoid basal cell carcinoma syndrome (NBCCS), medulloblastomas, basal cell carcinomas (BCCs), rhabdomyosarcoma
Type II	Ligand dependent with autocrine activation	Small-cell lung cancer, prostate, pancreatic, breast cancers
Type IIIa	Ligand-dependent, paracrine activation	Pancreatic, ovarian, prostate and colorectal cancers
Type IIIb	Ligand-dependent, reverse paracrine activation	B-cell lymphoma, multiple-myeloma and leukemia
Type IV	Regulation of stemness-determining genes	Cancer stem cells present in hematological malignancies and in solid tumors