Fig. 1. Ligand-activated PPAR induced changes associated with senescence and induced irreversible cell-growth arrest in 2BS and WI-38 cells. 2BS and WI-38 cells transfected with the expression plasmids pcDNA3.1 (vector) or pcDNA-PPAR (PPAR) were analyzed for the relative senescence markers (all transformants of 2BS cells at PD42 and WI-38 cells at PD37). Cells were treated with 20 µM troglitazone or DMSO (vehicle) as indicated. (A) Western blot analysis of PPAR overexpression in PPAR-transfected cells compared with vector-transfected cells. Western blotting was performed using specific antibodies against PPAR as indicated. The β-actin lane serves as a loading control. (B) Vector-transfected and PPAR-transfected cells were stained for SA-β-gal activity (blue), a classical marker of senescence. (C) Growth curves of vector-transfected and PPAR-transfected cells were determined by the MTT assay. Values are the mean ± s.d. of triplicate points from a representative experiment (n=3), which was repeated three times with similar results. Values accompanied by different symbols are statistically significantly different from each other. (D) Flow-cytometry analysis of vector-transfected and PPAR-transfected cells. Each experiment was performed at least three times. The table shows the representative data. The graph depicts data from three independent experiments (means ± s.d.). ^*P0.05 vs vehicle-treated vector cells; ^#P0.001 vs vehicle-treated vector cells.