SHH and pulmonary fibrosis: Although the inhibition of Shh signaling does not neutralize the development of bleomycin-induced pulmonary fibrosis, the stimulation of Shh genes expression leads to the development of more severe cases of pulmonary fibrosis [215,216], and during the development of bleomycin-induced fibrosis, expression levels of Shh-dependent genes are increased in airway cells and alveolar epithelium [216].