PTCH1 and pulmonary fibrosis: Accumulating evidence indicates cross talks between SHH pathway and TGF-β signaling in a number of diseased conditions including gastric carcinoma [21], melanoma bone metastasis [22] and pulmonary fibrosis [20] that are independent of patched-1 (PTCH-1)- or smoothened (SMO)-inhibition in which PTCH-1 and SMO are the two major membrane spanning receptors for SHH.