Regulation of gene expression includes a wide range of mechanisms that are used by cells to increase or decrease the production of specific
gene products (
protein or
RNA), and is informally termed
gene regulation. Sophisticated programs of
gene expression are widely observed in biology, for example to trigger developmental pathways, respond to environmental stimuli, or adapt to new food sources. Virtually any step of gene expression can be modulated, from
transcriptional initiation, to
RNA processing, and to the
post-translational modification of a protein.