Peptides are small messengers that cells use to send signals by binding to...

https://zanessplendidcolumns.opalvector.com/posts/why-do-labs-measure-secretion-after-peptide-stimulation

Peptides are small messengers that cells use to send signals by binding to receptors on their surfaces. In the lab, researchers use peptides to study how receptors respond and select specific signaling pathways