Fig. 4

a Western blot demonstrates the expression level of BCL6 in SU-DHL-6 (MEF2B-positive) before and after the knockdown of MEF2B by its specific siRNA. b Western blot analysis of MEF2B and BCL6 proteins using the total cell lysates derived from SU-DHL-2 (MEF2B-deficient) following the transfection with MEF2-WT together with ΔMADSMEF2 and PGL-BCL6-promoter/Luc before and after the transfection with siRNA specific to cDNA encoding region of the C-terminal domain of MEF2B. Actin was used as an internal control for loading and transfer. c Electrophoretic mobility shift assay (EMSA) demonstrates the DNA-binding activity of the transcription factors BCL6 and AP-2α supershift analysis using specific anti-AP-2α, BCL6, and MEF2B antibodies demonstrates the involvement of MEF2B, BCL6, and AP-2α proteins in the formation of the transcriptional complex of BCL6 gene. The competitor was used as a negative control for the DNA-binding activity of the transcription factors. Data are representative of three independent experiments. d Lucieferase assay demonstrates the activity of the BCL6 promoter in response to the expression of MEF2B-WT or C-terminal truncated MEF2B (ΔMADSMEF2) in SU-DHL-2 cells