Abstract: The cellular response to cosmetic products has been characterized on the molecular level through the use of gene and protein expression technologies. Nucleic acid and protein molecules, the expression of which are induced or repressed in response to exposure to cosmetics, are identified according to a temporal pattern of altered expression post exposure. Methods are disclosed that utilized these cosmetics-regulated molecules as markers for effectiveness of cosmetics. Other screening methods of the invention are designed for the identification of compounds that modulate the response of a cell to exposure to cosmetics. The invention also provides compositions useful for drug screening or pharmaceutical purposes.