SHH and pachyonychia congenita: More specifically, the enhanced expression of hedgehog signaling elements, including sonic hedgehog ligand (SHH) and glioma-associated oncogene homolog-1 (GLI-1) that acts as a zing finger transcription factor, has been observed in PC epithelial cells and/or stromal compartment of tumors during disease progression to aggressive, metastatic and AI PC [12–18].