Human skin gene expression doesn't correlate with protein expression? Unless both parameters are quantified.

Many cosmetic companies utilize in vitro gene array studies to display significant stimulation or inhibition of various human skin biomarkers to validate in vivo actions that are reported to enhance dermal health. This follows the central dogma of DNA-to-RNA results in protein expression; however, gene and protein expressions do not usually correlate. Unless both gene and protein expressions are quantified which require further investigational time and investment. Where data are available, this short commentary displays the in vitro comparison of four human skin biomarkers for the gene and protein expressions of the stimulation of collagen type I and elastin and the inhibition of matrix metalloproteinases 1 and 3, when equol was tested. The results demonstrate a good correspondence between gene and protein expressions for the human skin biomarkers tested.