Figure 2.

The use of PQ as a positive control to distinguishes senescent inducers from nonactive compounds. Representative images from which %SA were calculated, reflecting the dynamic range of %SA values. Human astrocytes were stained for SA-β-gal activity (top) and DAPI (middle) to identify SA-β-gal positive cells (eg, arrows). Left most column shows the positive control PQ (%SA = 47.8); second from the left shows the top hit, 3, 3’-Iminodipropionitrile (%SA = 49.6); second from right shows a designated nonhit with a %SA close to the average for all compounds, toluene (%SA = 32.8) and the right most column shows the compound with the lowest %SA, triphenyl phosphate (%SA = 10.4).