The free-radical scavenger L-NAC blocks As₂0₃- but not PD184352/UCN-01–induced apoptosis in MM cells.

8226 (A), H929 (B), and U266 (C) MM cells were exposed to either 1 μM As₂O₃ or 10 μM PD184352 + 150 nM UCN-01 for 24 or 48 hours after 2 hours pretreatment of 10 mM L-NAC, after which the percentage of apoptotic cells was determined by evaluating Wright-Giemsa–stained cytospin preparations as described in “Materials and methods.” For all panels: ■ indicates control; ▪, LNAC; ░, PD + UCN; ▧, PD + UCN + LNAC; ▨, As₂O₃; ▩, As₂O₃ + LNAC. Values represent the means ± SD for 3 separate experiments performed in triplicate.