<P> In multicellular organisms, gene regulation drives cellular differentiation and morphogenesis in the embryo, leading to the creation of different cell types that possess different gene expression profiles from the same genome sequence . This explains how evolution actually works at a molecular level, and is central to the science of evolutionary developmental biology ("evo - devo"). </P> <P> The initiating event leading to a change in gene expression includes activation or deactivation of receptors . </P> <P> Any step of gene expression may be modulated, from the DNA - RNA transcription step to post-translational modification of a protein . The following is a list of stages where gene expression is regulated, the most extensively utilised point is Transcription Initiation: </P> <Ul> <Li> Chromatin domains </Li> <Li> Transcription </Li> <Li> Post-transcriptional modification </Li> <Li> RNA transport </Li> <Li> Translation </Li> <Li> mRNA degradation </Li> </Ul>

Which of these types of gene regulation occurs earliest in the process of gene expression