Research from the STEP trial program shows that 1.0 mg is where the dose-response curve starts to steepen meaningfully
However, if you happen to be choosing between the two, GHK-Cu is usually the better option since it helps the body use copper in a way that supports healthy skin, even being compared to Matrixyl Does GHK Combine with Copper Ions Naturally
Immunoreactivity assays for endogenous DSIP-like material in tissue and CSF have used antibodies whose specificity for the nonapeptide versus related peptides has not always been rigorously established (Kovalzon & Strekalova, 2006)
Arch Biochem Biophys 33:6577 Miller G, Schlauch K, Tam R, Cortes D, Torres MA, Shulaev V, Dangl J, Mittler R (2009) The plant NADPH oxidase RBOHD mediates rapid systemic signaling in response to diverse stimuli