To characterize transcription factors (TFs) that binds to a specific promoter or that regulate the expression of a specific gene via its upstream promoter, two common approaches are applied. First is to employ gel shift assay with DNA binding sites of TFs that are silico-identified within the promoter. Second is to removal or knockout the binding site(s) of a specific TF in order to measure whether the expression of a promoter-linked reporter is increased or decreased. Often, a series of reporter constructs with the promoter deletions or mutations need to make because many binding sites of one or a few TFs are present within a promoter. Signosis has developed a fast method to facilitate the characterization of promoters through a revised TF activation array. This assay will help to test whether selected 48 or 96 TFs bind to the promoter or not.