A. Archazolid A decreases the anti-apoptotic protein survivin. Immunoblots from Jurkat cells treated with Archazolid A (Arch, 10 nM, left panel) or DBZ (50 μM, right panel) for the indicated times and probed with antibodies for survivin, XIAP, IAP1, and IAP2 are shown. Immunoblots for tubulin indicate equal loading. n = 3. Bar graphs display the quantitative evaluation of survivin expression. B. Immunostainings for survivin (green) and actin (red) after treatment with/without Archazolid A (Arch, 10 nM, 24h) and DBZ (50 μM, 24h) is shown. Scale bar 10 μm. C. Archazolid A (Arch) and DBZ do not interfere with survivin mRNA expression. Survivin mRNA levels from Jurkat cells treated with Archazolid A (1 and 10 nM) and DBZ (50 μM) for 24h are shown. Not significant (ns), Archazolid A: One-Way ANOVA, DBZ: paired t-test, n = 3. D. Archazolid A (Arch) induces S-phase cell cycle arrest of Jurkat cells. Cell cyle analysis and apoptosis measurement after aphidicolin synchronization (24h) and subsequent treatment with Archazolid A for indicated times is shown. Control cells (untreated, Archazolid A 0 nM) are indicated in red, Archazolid A (Arch, 10 nM) treated cells are indicated in blue. One representative out of three independent experiments is shown.