Before revision:  We define a statistical detection problem over a reaction pathway consisting of three species: an inducer, a transcription factor (TF) and a gene  , where the inducer can activate the TF and an active TF can bind to the gene promoter.
After revision:  We define a statistical detection problem over a reaction pathway consisting of three species: an inducer, a transcription factor (TF) and a gene promoter , where the inducer can activate the TF and an active TF can bind to the gene promoter.