CTCF and malignant colon neoplasm: In U2OS cells and HCT116 human colon cancer cells, CTCF and Rad 21 promote the recruitment of RNA Pol II to the TERRA promoter region and shRNA-mediated depletion of Rad21 or CTCF results in loss of RNA Pol II binding at the TERRA promoters and consequent decrease in TERRA levels [64].