UBTF and cancer: They also demonstrated that the binding site of Pol I regulatory proteins such as UBF and basonuclin is located downstream and upstream of UCE and CP, respectively, which were initially identified as Pol I regulatory sites by their association with subunits of Pol I. The CpG island methylation level at the promoters of tumor suppressor genes is widely known to contribute to tumorigenesis and tumor progression in many types of cancer by changing the promoter activity [55].