GHK Cu is a naturally occurring tripeptide in human plasma. Levels average 200 ng ml at age 20 and drop to 80 ng ml by age 60 (Pickart et al., 2020). That decline tracks with GHK Cu Copper Peptide in LA 3,356+ Reviews Expression and Purification of Recombinant GHK Tripeptides Are Able to Protect against Acute Cardiotoxicity from Exposure to Waterborne Copper in Zebrafish How GHK Peptide Works Signaling GHK acts as a switch for skin repair: Interacts with adenosine receptors reduces inflammation Activates MAPK ERK, PI3K Akt, TGF pathways Stimulates fibroblasts & keratinocytes boosts collagen, elastin GHK Cu: The Regenerative Peptide for Skin, Hair, and Healing Pulse & Remedy