TP53 and cancer: TP53 mutations (66 out of 68) occurred with mutually exclusivity to CTCF mutations (p = 9.28 × 10−6, Figure 6B,C); whereas mutations in MED13L, encoding a subunit of the Mediator transcriptional co-activation complex, co-occurred with CTCF mutations in 13 out of 23 cancers (p = 2.64 × 10−5, Figure 6B).