Figure 1.

Cdc20 and securin protein expression is downregulated in oxidative stress–induced senescent WI-38 fibroblasts.A, human diploid WI-38 fibroblasts were treated with sublethal hydrogen peroxide (450 μM) for 2 h. Cells were washed with PBS and recovered in complete medium for 14 days. Cells were collected and cell lysates were subjected to immunoblot analysis using protein-specific antibody probes. Untreated cells were used as control. Ponceau S staining shows equal total protein loading. Quantification of protein band intensity is shown at the bottom of each blot. B–D, premature senescence was induced in WI-38 cells as described in (A). Cells were then stained to detect senescence-associated β-galactosidase activity. Representative images are shown in (B), quantification is shown in (C). The scale bar represents 100 μm. The percentage of cells possessing enlarged and flat morphology (senescence-associated (SA) cell morphology) is shown in (D). Values in (C) and (D) represent means ± SEM; statistical comparisons were made using the student’s t test. ∗p < 0.001.