Effects of Copper Tripeptide on the Growth and Expression of Growth Factors by Normal and Irradiated Fibroblasts Jeffrey D. Pollard, Susan Quan, Thomas Kang, R. James Koch, 2005 Defy GHK Cu (glycyl L histidyl L lysine) is a naturally occurring copper binding peptide found in human plasma. As levels decline with age, so may its support of the biological processes involved in collagen production, skin The tripeptide GHKCu complex ameliorates lipopolysaccharideinduced acute lung injury in mice Oncotarget GHK Cu vs NAD+: Which Longevity Peptide Should You Take or Stack?