Oral squamous cell carcinoma (OSCC) invades surrounding tissues by upregulating matrix metalloproteinases (MMPs) -2 and −9, which causes over-expression of the Hedgehog signaling proteins Shh and Gli-1 and degradation of the extracellular matrix, thereby creating a “highway” for tumor invasion. Here, GLI1 is linked to oral cavity squamous cell carcinoma.