Hedgehog (Hh) signaling is an important factor in growth and patterning during 
embryonic development. A mutation in Patched, Smoothened or Gli1, which regulate 
the Hh signaling pathway, might lead to the onset of glioblastoma, basal cell 
carcinoma, medulloblastoma and rhabdomyosarcoma. Recently, Hh signaling has been 
reported to be activated in a ligand-dependent manner, contributing to 
carcinogenesis and cancer progression. Hedgehog signaling is reactivated in 
various types of cancer, and this contributes to cancer progression by 
facilitating proliferation, invasion and cell survival. Moreover, Hh signaling 
is associated with several other signaling pathways that contribute to cancer 
progression. These observations indicate that controlling Hh signaling might 
become a target for novel molecular targeting therapy.