ADAR1-p110 and ADAR1-p150 regulate the processing of the pri-miR-Let-7d and mature Let-7d in such a way that the sub-expression of the latter deregulated, in turn, the expression of COL3A1 and SMAD2, proteins involved in the development of idiopathic pulmonary fibrosis. The gene discussed is SMAD2; the disease is pulmonary fibrosis.