text: There are several different techniques to detect regulatory genes, but of the many there are a certain few that are used more frequently than others.  One of these select few is called ChIP-chip.  ChIP-chip is an in vivo technique used to determine genomic binding sites for transcription factors in two component system response regulators. In vitro microarray based assay (DAP-chip) can be used to determine gene targets and functions of two component signal transduction systems. This assay takes advantage of the fact that response regulators can be phosphorylated and thus activated in vitro using small molecule donors like acetyl phosphate.