For long time GLI1 gene has been considered as a unique member of the HH-GLI pathway because at that time no somatic mutations have been reported in tumors and it was thought that oncogenic potential of GLI1 could be manifested primarily through either gene amplification or an alternative splicing when novel truncated GLI1 splice variant, tGLI1, with a gain-of-function characteristics was discovered in glioblastoma multiforme and breast cancer [54,61]. This evidence concerns the gene GLI1 and breast carcinoma.