We next analyzed the expression levels of canonical SHH signaling components—such as PTCH1, PTCH2, SMO, SUFU, and GLI1 proteins—in cultured human lung cancer cells (H1299, A549, HCC827, and H1975) and normal human lung fibroblasts (MRC-9 and WI38) by western blot analysis. Here, PTCH2 is linked to lung cancer.