GHK-Cu (glycyl-L-histidyl-L-lysine copper complex) is a naturally occurring copper-binding tripeptide that has attracted sustained scientific interest due to its broad biological activity profile. First identified in human plasma, this peptide–copper complex has been extensively studied for its regulatory influence on cellular signaling, gene expression, and tissue remodeling pathways. In laboratory settings, GHK-Cu is recognized for its stability and ability to modulate multiple molecular targets, making it a versatile compound in peptide-based research models.