GHK Cu vs AHK Cu: Which Copper Peptide Is More Effective? GHK Cu vs NAD+: Which Longevity Peptide Should You Take or Stack? GHK Cu is getting a lot of attention right now, and for good reason. This is not just a skin peptide. It's a copper binding tripeptide with documented effects on gene expression, collagen synthesis, GHK Cu Peptide Therapy: The Definitive Clinical Guide to Gene Modulation, Protocols, and Efficacy