Figure 1. Increased epithelial cell senescence occurred in idiopathic pulmonary fibrosis (IPF). (A) The mRNA levels of p16 and p21 were measured by Q-PCR, **P < 0.01. (B) The protein levels of collagen I, p16 and p21 were measured by Western blot. (C) SA-β-gal activity was revealed by X-gal staining. The expression of p16 was determined by immunohistochemical analysis. (D, E) The normal lung (Con) and lung of a patient with idiopathic pulmonary fibrosis (IPF) were double stained with E-cadherin and p21 (D) or p16 (E) by immunofluorescence.