Figure 4: SMAD7 overexpression induces apoptosis and blocks cell cycle entry in fibroblasts derived from human Peyronie's disease plaque. Fibroblasts were transfected with an empty PEI25k/pCMV5 vector or a PEI25k/ pCMV5-Smad7 (pSmad7) polyplex for 48 h and were then treated with TGF-β1 (10 ng ml−1) for 1 h. (a) Terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling assay. Nuclei were labeled with the DNA dye DAPI. One bar indicates 25 ìm. (b) The number of apoptotic cells is presented as a percentage of total cells per field. (c) A representative Western blot for cyclin D1. Whole-cell extracts were fractionated in a sodium dodecylsulfate-polyacrylamide gel. (d) Data are presented as the relative density of each protein compared with that of β-actin. The relative ratio measured in the no treatment group was arbitrary presented as 1. Each bar depicts the mean values (± s.e.) from four experiments per group. **P < 0.01, ***P < 0.001 by ANOVA. PEI: poly (ethyleneimine); TGF-β1: transforming growth factor-β1; SMAD7: decapentaplegic homolog 7; DAPI: 4,6-diamidino-2-phenylindole.