Fig 1: Sodium butyrate and lopinavir treatment induce senescence in intestinal epithelial cells (IECs).IECs were incubated for 5 days with 10 mM sodium butyrate (NaBu) or 3 days with 30 µM lopinavir (Lopi). Control cells were incubated with vehicle (V). Several hallmarks of cellular senescence were examined. a The number of cells positive for senescence-associated (SA) β-galactosidase activity was assessed in four (NaBu) or three (Lopi) independent experiments. For each data set, at least 100 cells were evaluated per condition. Representative images for SA-β-galactosidase activity are shown. The scale bar is 50 µm. b The cell size was measured for 129–241 cells/condition. c Cell proliferation (EdU incorporation) was scored in 128–181 cells/condition. Nuclear dystrophy was monitored by immunocytochemistry with antibodies against lamin A. Scale bar is 20 µm. d The abundance of p53 and p21 was reduced in senescent IECs. IECs attached to the growth surface were harvested, and the abundance of p53 and p21 was determined for crude extracts. Actin was used to normalize ECL signals to the vehicle controls. The molecular mass of marker proteins in kDa is shown at the right margin of the blots. Graphs represent results for three to six independent experiments. a–d Data are shown as average + SEM. Student’s t-test identified significant differences between vehicle controls and treated samples; **p < 0.01; ***p < 0.001.