SENP1 induces cell death. A: SENP1 tagged to GFP in INS-1 832/13 cells and the loading control β-actin. B: INS-1 832/13 cells transduced with Ad-GFP (open bars) or Ad-GFP-SENP1 (filled bars) treated with IL-1β for 24 h and stained for TUNEL (red) and nuclei (DAPI, blue). Representative images (left) and quantification of GFP+ and TUNEL+ cells (arrows) as %total GFP+ cells (right) are shown. Scale bars, 15 μm. C: immunoblotting for cleaved caspase 3 (CC3) and β-tubulin (left) from INS-1 832/13 cells transduced with Ad-GFP (open bars) or Ad-GFP-SENP1 (filled bars) and treated with IL-1β for 24 h. Quantification by densitometry relative to Ad-GFP group (right). C: human islets transduced with Ad-GFP (○) or Ad-SENP1 (●) were treated, as indicated, for 48 h. Islets sections immunostained for GFP (green), CC3 (red), and nuclei (DAPI; blue). Representative images (left) and GFP+ CC3+ cells (arrows) as %total GFP+ cells (right) are shown. Scale bars, 10 μm. *P < 0.05, **P < 0.01.