Cell signalling pathways are used to maintain homeostasis. Enzymes are normally present in adequate concentrations but whenever the need for a particular enzyme or protein arises, cell signalling is used.
Signal is sent to that particular cell, the process of genetic expression is activated. A gene that codes for that particular protein(enzyme of interest) goes through transcription, where that genes DNA is copied to make a messenger RNAmolecule, which is further expressed by a process called Protein expression. Lastly, transported to that particular area where it is needed.
