2-O-methylation refers to the methylation of the 2 hydroxyl group of the ribose within an RNA nucleotide. 2'-O-methylation is found in the five-prime cap of mRNAs in higher eukaryotes. It is involved in differentiating between self and non-self mRNA. Without the 2′-O-methylation mark the immune system triggers higher levels of type 1 interferon activity. While this modification is not currently known to be a response to any particular phenomenon, not everything is fully understood about the mechanisms of this modification due to the difficulty of studying small RNA molecules. However, the effect on RNA stability this modification has could be regulated to modulate transcript levels.