Regulatory agencies believe microarray data could be extremely useful in testing prospective chemical products and investigating safety problems after chemicals have been marketed. However, it has not yet been clearly established how this information will be used by agencies in the approval of pharmaceuticals and other chemicals--or even whether companies will be required to submit microarray data. Although some private companies are already voluntarily submitting microarray data along with their drug and pesticide applications, others are hesitant to do so. Most of the stakeholders involved agree that standardization of microarray experiment procedures and of genomic signatures are key to the broad acceptance and use of these data.