GHK Cu: My secret weapon for skin, hair, and healing, I use it two ways topical cream for my face, and subQ injections 3x a week., It boosts collagen, tightens skin, helps hair grow, and even Cellular Morphine Tolerance Produced by Arrestin 2 Dependent Impairment of Opioid Receptor Resensitization Journal of Neuroscience 2 weeks in on GHK Cu and the glow is REAL. Brighter complexion More even skin tone Less breakouts Softer fine lines Thicker, fuller hair This is just PDF) The Effect of the Human Plasma Molecule GHK Cu on Stem Cell Actions and Expression of Relevant Genes