It was found that the expression of SHH, smoothened (Smo), patched (Ptch), and Gli1 pathway proteins was increased significantly in idiopathic pulmonary fibrosis (IPF), suggesting that the SHH pathway may accelerate pulmonary fibrosis via alteration of self-renewal and differentiation of lung stem cells [70–72]. Here, PTCH1 is linked to idiopathic pulmonary fibrosis.