In 1992 a new approach for identifying differentially expressed genes was described by Liang and Pardee (1). Their method allowed the simultaneous differential display of mRNA from two or more cell types by means of the polymerase chain reaction (PCR). In a subsequent study demonstrating the technique Bauer, et al. (2) named it differential display reverse transcription PCR (DDRTPCR) in accordance with the series of steps required to identify differences in gene expression. Differential mRNA display offered a number of advantages over existing cDNA library hybridization based methods used to identify differentially expressed genes. Firstly, screening is fast, reproducible, and technically easier than existing protocols, especially since cDNA libraries do not need to be constructed. Secondly, PCR amplification not only detects low abundance mRNA species, but also allows the comparison of gene expression from very small amounts of starting material such as vascular biopsies.