The expression of pSmad2/3: Smad-7 in smaller arteries of 100–199 μm was 37.5%:31.3% in IPF and 5.9%:4.6% in NCs, whereas in medium arteries of 200–399 μm, it was 21.3%:17.4% in IPF and 2.8%:2% in NCs. Here, SMAD7 is linked to idiopathic pulmonary fibrosis.