(a) Comparison of Myc locus between human and mouse. The susceptibility regions for prostate cancer (PrCa), chronic lymphocytic leukemia (CLL), breast cancer (BrCa), colorectal cancer (CRC) and bladder cancer (BlCa) are marked. Red vertical lines mark the location of the Tcf7l2-binding CRC Myc enhancers in the two species. The lower panel shows the regional conservation probability predicted by PhastCons (hg19 assembly, UCSC) with non-overlapping sliding windows for the whole region and each enhancer locus with a size of 500 bp and 10 bp, respectively. (b) Deletion of Myc-196 and Myc-540 enhancer elements does not affect Myc expression in the colon as determined by qPCR analysis (Myc-196−/− n = 2, Myc-540−/− n = 3 and wild-type n = 5). See Figure 1—source data 1 for details. (c) Mutation of the Myc-CTCF site causes loss of CTCF and Rad21 binding at the Myc locus (top panel). Binding of CTCF and Rad21 at a control Actb locus is not affected. Red and black arrowheads denote binding sites at Myc and Actb loci, respectively; green: Myc-CTCFmut/mut, blue: wild-type. The gene body for Myc and Actb is shown below the respective panels. The qPCR analysis reveals that despite loss of CTCF/cohesin binding, the expression of Myc mRNA is not altered in the colon (for qPCR, Myc-CTCFmut/mut n = 4, wild-type n = 3). See Figure 1—source data 1 for details. Error bars denote one standard deviation.