The other microRNA, miR-155, is regulated both by epigenetic methylation of the CpG islands in its promoter region and by epigenetic acetylation of histones H2A and H3 at the miR-155 promoter (where acetylation increases transcription). Measured by two different methods, miR-155 was over-expressed in sporadic colorectal cancers by either 22% or 50%. When miR-155 was elevated, hMSH2 was under-expressed in 44% to 67% of the same tissues (and hMSH6 is likely under-expressed as well, and also unstable in the absence of hMSH2).