Co-operative induction of apoptosis by ABT-199 with etoposide and AC220.

Cells were incubated with 10 nM ABT-199 (199, turquoise), 10 nM pladienolide B (PLB, red), 1 μM torin1 (green), 1 μM etoposide (orange) and 10 nM AC220 (mauve) or the indicated combinations (bright blue bar, height = effect with both agents in combination–sum of effects with agents individually). (A) After 4 hours cells were fixed and processed for Cytochrome C release. (B) After 4 hours DiOC6 was added for a further 75 minutes and 7-amino actinomycin D for the last 30 minutes. (Mean+/- SD for n = 3). Fold excess additivism (FEA) is shown on the figures and was calculated as a ratio of observed to expected values after corrections according to the Bliss algorithm (see methods). Asterisks indicate observed values significantly higher than expected values (P<0.05).