Peptides are tiny messengers that cells use to communicate by binding to...

https://extra-wiki.win/index.php/Why_Use_Cultured_Cells_Instead_of_Whole_Animals_for_Signaling_Work%3F

Peptides are tiny messengers that cells use to communicate by binding to specific receptors. Researchers study how peptides interact with these receptors to understand which signals they trigger, like changes in intracellular calcium levels