Figure 2. Effects of NaHS on cell senescence in CSE-stimulated A549 cells. A549 cells were cultured with and without 3% CSE and/or 100, 200, or 400μM NaHS for 48 h. Cell senescence was performed by examining the (A) the SA–β-gal activity. (B) the mRNA level of p21 by Real-time PCR. (C, D) the protein levels of p53 and p21 by Western blot. (E–G) The mRNA levels of IL-6, IL-8 and MMP-2 were detected using Real-time PCR. **P<0.01, significantly different from control cells [3%CSE (-) and NaHS (-)]; #P<0.05, ##P<0.01, significantly different from cells treated with 3%CSE only.