HOPX and idiopathic pulmonary fibrosis: These conditions might be responsible for the reduction of genes involved in alveolar maintenance, such as HOPX. In addition, IPF is characterized by a “hyper-responsive” regenerative loop due to re-activation of developmental pathways including sonic hedgehog44, TGF-β45, and Wnt signaling46, resulting in inappropriate proliferation of alveolar epithelial precursors, which are also prone to die due to replicative senescence, and presumably also due to loss of HOPX.