Aberrant activation of Hh pathway in cancers is caused either by mutations of negative regulator in the pathway such as Patched in basal cell carcinomas or through ligands overexpression such as Shh in pancreatic cancer.[26] The downstream transcription factors, Gli1 2 and 3, bind to the same DNA sequence (5'-GACCACCCA-3').[27, 28] Gli2 and 3 have both transactivation and repression domains, whereas Gli1 has been suggested to function only as a transactivator. This evidence concerns the gene SHH and cancer.