The hormone, also called the ligand is considered as_________. (a) First messenger (b) The Second messenger (c) Both (a) and (b) (d) None of the above
Ligand (first messenger): A chemical messenger that binds specifically to one receptor (e.g. proteins, steroids, hormones, neurotransmitters, small organic molecules such as nitric oxide (NO)). Signaling cascade: The interconnection of individual steps in a signaling pathway.
