Based on one of the leading encyclopedic resources in cell and molecular biology worldwide, this two-volume work contains more than 75% new content, not previously published in the Encyclopedia. All the other chapters have been carefully updated. The result is a comprehensive overview of the different functions of the various forms of RNA in living organisms, with each contributor carefully selected and an internationally recognized expert on his or her field. Special focus is on the different forms of expression regulation through RNA, with medical applications in the treatment of diseases -- from cancers and immune responses to infections and aging -- covered in detail. At least 45 of the 55 articles are new content previously not published in the Encyclopedia.