We analyzed the expression of SMAD-2 molecules in TGF-β-stimulated primary human fibroblasts isolated from healthy and IPF subjects at 4, 10, and 24 h after treatment with Hylach 1, Hylach 2, and the native HA when the anti-fibrotic and anti-inflammatory effects of these molecules were more marked. The gene discussed is SMAD2; the disease is idiopathic pulmonary fibrosis.