Different gene expression tools are discussed in this thesis. The techniques for RNA expression like Northern blotting, DNA microarrays, and real-time PCR will be presented. Also, promoter analysis methods including gel shift assays, reporter gene fusion, in vitro transcription, and chromatin immunoprecipitation assay will be discussed. In addition, techniques applied in protein expression: western blotting, two-dimensional electrophoresis, and immunoassays are reviewed.