Regulation of gene expression is controlled through the combinatorial action of multiple transcription factors, which function to activate or repress transcription via binding to cis -regulatory elements. Such regulatory elements are usually present in the promoter sequences located upstream of the transcription initiation sites of a target gene. Identification of functional target gene promoters that are regulated by a specific transcription factor is one of the most critical areas in understanding the molecular mechanisms that control transcription. Furthermore, identification of target gene promoters for normal and oncogenic transcription factors provides insight into the regulation of genes that are involved in control of normal cell growth and differentiation, as well as provide information critical to understanding cancer development.