sentences:  If one or the other of these two microRNAs is over-expressed, hMSH2 and hMSH6 proteins are under-expressed, resulting in reduced DNA mismatch repair and increased microsatellite instability.One of these microRNAs, miR21, is regulated by the epigenetic methylation state of the CpG islands in one or the other of its two promoter regions.Hypomethylation of its promoter region is associated with increased expression of an miRNA.