YY1 binds to the conserved YY1 binding motif in the FEN1 promoter region. A. Sequence alignment of the conserved YY1 binding motif in different proteins. B. EMSA analysis of YY1 binding to the YY1 binding motif in the FEN1 promoter. Recombinant YY1 was incubated with different biotin-labeled DNA probes. The sequences of the Probe N, Probe P, WT FEN1and MUT FEN1 can be found in Additional file 1: Table S6. The free probe and YY1/DNA complex were resolved in 5% native PAGE. C. EMSA assay on YY1 and FEN1 oligo in the presence of non-specific IgG or the anti-YY1 antibody. D. ChIP analysis of YY1 binding to the FEN1 promoter region. Specific YY1-bound DNA in MCF7 cell extracts was pulled down by an anti-YY1 antibody. The YY1-bound FEN1 sequence was amplified by PCR. The sequence for the FEN1 promoter specific primer can be found in the Additional file 1: Table S6 as FEN1 (YY1). The PCR product was analyzed by 1% agarose electrophoresis.