Inappropriate epithelial Shh target gene induction is sufficient to cause basal cell carcinoma (BCC), one of the most common tumors in Caucasians, with an incidence of over a million cases per year in the U.S. BCCs also have a striking reliance on adjacent stroma for continued growth and invasion, implying that non-cell autonomous factors influence the extent of Shh target gene induction in tumors [1-3]. This evidence concerns the gene SHH and basal cell carcinoma.