PDE4B and idiopathic pulmonary fibrosis: A lung fibrosis animal model alternative to bleomycin is strongly needed; in fact, Nintedanib, an approved drug for IPF (52), as well as the PDE4B inhibitor BI-101550 (53), were tested in BLM and silica models, even though the silica model is not fibrosis-specific and is associated with a strong inflammatory response.