This Note describes a novel rapid and direct quantitative method for examining the activity of genetic response elements. This method will provide an alternative to the classically used "reporter gene" activity assays. We show that a transfected genetic cis-regulatory element that responds to the transcription factor p53 gives a quantitative read-out at the RNA level that parallels that of an endogenous p53 responsive gene, p21 waf1/cip1. The correlation between the endogenous p21 gene expression in response to p53 and the transfected cis element is remarkable. This method is more direct and potentially faster than traditional promoter-reporter assays.