Application 3-indoleacrylic acid may be used in various microbiology studies to induce transcription of genes under the control of the trpE promoter. Biochem/physiol Actions Induces transcription of genes under the control of the trpE promoter.1 IAA also transcriptionally activates gene expression in plants.2,3 Some of the genes that are induced by IAA encode a family of proteins that contain nuclear localization signals that direct a β-glucuronidase reported protein into the nucleus.4