DNMT1 and colorectal cancer: Rhee et al. (2002) showed that disruption of either DNMT1 or DNMT3B resulted in partial methylation and simultaneous disruption of DNMT1 and DNMT3B resulted in global hypomethylation and reactivation of tumor suppressor genes in both in vitro and in vivo colorectal cancer models leading to reduced proliferation and tumor growth (Rhee et al. 2002).