In line with these regulatory properties of HH/GLI, uncontrolled and persistent HH/GLI activity has been causally implicated in the growth of various cancer entities, including malignancies of the skin, brain, lung, prostate, breast, the gastrointestinal and hematopoietic system [43,44,45,46,47,48,49,50,51,52,53,54,55,56,57,58]. This evidence concerns the gene GLI1 and cancer.