Nuclear proteasomal activity after addition of 10⁻⁷ M adriamycin in different U937 leukemic cell variants in the absence or presence of the PARP inhibitor 3-ABA.

(Left) −3-ABA. Nuclei from U937, Diff-U937, Retro-U937, and TUR cells were isolated and lysed after treatment with 10⁻⁷ M adriamycin for the time points indicated, respectively. Proteasome activity is expressed as lactacystin-sensitive suc-LLVY-MCA degradation. Data are given as mean ± SD (n = 4). (Right) +3-ABA. Time course of proteasome activity in lysates of nuclei from adriamycin-treated cells in the presence of 1 mM 3-ABA. Data are given as mean ± SD (n = 4). ▪, U937; ▴, Diff-U937; ●, Retro-U937; ▾, TUR.