CTCF and neoplasm: 22 Loss of CTCF binding via aberrant DNA methylation of critical control regions can induce epigenetic silencing of tumour suppressor loci or lead to activation of oncogenes.23, 24Ctcf heterozygous mice are prone to tumour development in various tissues including the uterus.25 This verifies CTCF’s role as a haploinsufficient tumour suppressor gene.