We have generated and validated degron alleles of UHRF1 and/or DNMT1 in several human colorectal cancer cell lines. We then used genomics and bioinformatics to precisely describe he DNA demethylation dynamics in these cells, leading to the conclusion that UHRF1 maintains DNA methylation in cancer cells not only by stimulating DNMT1. Proteomics and genetics lead us to conclude that UHRF1 regulates DNMT3A, DNMT3B and TET2 activity in addition to regulating DNMT1. The tools we have developed will be valuable for future research efforts, and our results advance our understanding of cancer epigenetics, with potentially important therapeutic applications.