Gene expression is the process by which information from a gene is used in the synthesis of a functional gene product. This book offers a comprehensive look into the science of gene expression and regulation. This book covers a full spectrum of topics such as actions of nuclear receptors, RNA processing, DNA methylation and imprinting, Epigenetics, Gene Expression and Regulation in Prokaryotes and Eukaryotes. Regulation of gene expression is thus critical to an organism's development. The focus is on scientific concepts and issues, rather than specific organisms or experimental approaches.