A: Reporter assay comparing the effect of 50 μM of 79-6 on the repressor activity of GAL4-BCL6BTB, GAL4-KaisoBTB, GAL4-HIC1BTB or GAL4-PLZFBTB, compared to GAL4-DBD alone. The Y-axis shows fold repression in the presence of vehicle (black bars) compared to 79-6 (grey bars). B: Quantitative chromatin immunoprecipitation was performed in SU-DHL6 DLBCL cells to detect binding of BCL6, N-CoR and SMRT to the ATR promoter in the presence of vehicle (black bars) or 125 μM of 79-6 (grey bars). The Y-axis shows fold difference in enrichment of ATR in the various conditions. C: mRNA abundance of the BCL6 target genes ATR, TP53, CD69, p21 and CD44, and the non-target genes B2M, PCNA and HPRT was measured in SU-DLH6, SU-DHL4 (both BCL6 dependent) and Toledo (BCL6 independent) DLBCL cell lines exposed to vehicle or 50 μM of 79-6 for 8 h. The Y-axis shows 79-6 mediated fold induction of each gene normalized to RPL13A and relative to vehicle (DMSO). D: Dose-effect curves for a panel of 8 DLBCL cell lines exposed to increasing concentrations of 79-6 for 48 h. OCI-Ly7, OCI-Ly1, SU-DHL6, SU-DHL4, OCI-Ly10 and Farage are BCL6-dependent, and Toledo and OCI-Ly4 are BCL6-independent negative controls. Cell viability was determined by luminescent ATP quantization. The value between parentheses represent the drug concentration (in mM) that inhibits the growth of cell lines by 50% compared to vehicle (GI50). Assays were performed in biological triplicates, with the averages of these plotted. Error bars represent the SEM for replicates. See also .