In recent years, one of the most quickly incorporated methods in biomedical research has been microarray technology. Microarrays have been designed for the purpose of genotyping (e.g., SNP analysis), expression analysis (mRNA, miRNA, exon arrays), chromatin immunoprecipitations (ChIP-on-chip technology), and DNA sequencing. In this chapter we will focus on the application of DNA microarrays in gene expression analysis of mRNA. This technology allows for the simultaneous analysis of transcription patterns of literally thousands of genes, making it a very powerful approach. Hematopoietic sub-populations are relatively easy to obtain by using fluorescence-activated cell sorting or magnetic bead cell separation. Over the last decade, the combination of these purification techniques with microarray analysis has resulted in an enormous gain of knowledge of blood lineages and their development.
