Since the introduction of gene expression microarray technology, the number of applications and publications based on it has grown enormously. Nowadays, there is almost no institution or university in the field of molecular biology that has no genomic facility helping to apply this technique. Microarrays, an ordered assembly of thousands of probes, have the ability to allow the simultaneous determination of the expression levels of thousands of genes. This technique was used to describe gene programs that underlie various cellular processes, such as immunity and hormone responses, as well as to refine classifications of neoplasias, and to define diagnostic molecular markers for diseases. However, one drawback of the microarray technique is that, the more genes are tested, the higher the risk of identifying false positives as a result of random effects. Furthermore, biological and technical variations, including the microarray design, can affect the precision of microarray results. More difficult situations are found when working with complex multicellular tissue samples as compared to cell line experiments. The outcome of these microarray experiments can result in low fold changes and low signal intensities for differentially expressed genes, which makes it difficult to detect regulated genes reliably. Therefore, the identification of differentially expressed genes requires independent confirmation. Quantitative real-time reverse transcriptase–polymerase chain reaction (qPCR) is the method of choice because of its broad range of linearity, high sensitivity, and reproducibility and because it can be easily adapted to test several hundreds of transcripts.