Curcumin blocks HDAC activity. A. Curcumin-treated DAOY cells (6 hours) were lysed and subjected to a fluoremetric HDAC activity assay as described in Materials and Methods. Data represent the average of the mean ± SEM of two independent experiments done in triplicates B. C. Expression levels of various HDAC family members (B) and phosphorylation level of HDAC4/5/7 (C) in DAOY cells treated with curcumin for 3, 15 and 24 hours. Representative immunoblots are shown. GAPDH immunoblots indicate loading of equal amounts of protein. Numbers below immunoblots in B are the mean of the intensity of three independent experiments, normalized to control cells at each time point and concentration. D. Subcellular localization of HDAC4 (green) in DAOY cells. Incubation with curcumin (6 hours) did not significantly affect the cellular distribution of HDAC4. Nuclei are indicated by DNA (blue). Bar, 30 μm.