In the urethral stricture tissue, the expression of Igfbp3 was higher than that in the normal urethral group, the expression of smad2 and smad3 seemed unchanged, while the expression levels of p-smad2 and p-smad3 in the urethral stricture tissue were higher than normal urethral tissue (Fig. 4B). The gene discussed is SMAD3; the disease is Urethral stricture.