ETO enhancement of Bcl-6 repression is dependent on HDAC activity. (A) 293T cells were transfected with the Bcl-6 binding site containing reporter construct (B6BS-tk-luc) and with the empty Bcl-6 vector (lane 1), Bcl-6 plus the ETO empty vector (lane 2), and Bcl-6 plus ETO (lane 3). After 4 hours of transfection, 2.5 μM SAHA or the same volume of ethanol was added. After 24 hours, the transcriptional output was determined by luciferase assays normalized to an internal control (renilla). Four repeats were performed to determine standard deviations. (B) Twenty microliters of the same lysates used for luciferase assays were run on 15% SDS-PAGE and were immunoblotted for myc-tag (Bcl-6), HA (ETO), and β-actin. Error bars represent SD of 4 experiments.