Fig 6.

 Effects of retrovirally transfected apolipoprotein J (apo J) against SIPS induced by 5 repeated subcytotoxic stresses using senescence-associated β-galactosidase (SA β-gal) activity as criteria. The cells were exposed to 5 repeated subcytotoxic 1-hour stresses with 30 μM tert-butylhydroperoxide or 2-hour stresses with 4 % ethanol. At 48 hours after the last stress, cells were seeded in 60-mm culture flasks at a low density of 700 cells/cm². The next day, the percentage of cells positive for the SA β-gal activity was determined. Results are expressed as percentages of the total cell population and are means of 4 independent experiments ± SD. Black columns: WI-38 human diploid fibroblasts (HDFs) transfected with the PLXSN control vector; white columns: WI-38 HDFs transfected with the PLXSN/apo J vector