CTCF and central nervous system cancer: Other modules can also be affected by the anomalous methylation; the hypermethylation of CTCF-binding sites comprises its binding with the insulator protein CTCF in glioma, permitting an enhancer to interact with PDGFRA, which is a glioma oncogene (Flavahan et al., 2016) and blocking differentiation by disassociating SOX2 from putative enhancers (Modrek et al., 2017).