The development of the polymerase chain reaction (PCR), for which Kary Mullis received the 1992 Novel Prize in Chemistry, revolutionized molecular biology. At around the time that prize was awarded, research was being carried out by Russel Higuchi which led to the discovery that PCR can be monitored using fluorescent probes, facilitating quantitative real-time PCR (qPCR). In addition, the earlier discovery of reverse transcriptase (in 1970) laid the groundwork for the development of RT-PCR (used in molecular cloning). The latter can be coupled to qPCR, termed RT-qPCR, allowing analysis of gene expression through messenger RNA (mRNA) quantitation. These techniques and their applications have transformed life science research and clinical diagnosis.