Master Molecular Switch (IMAGE) University of Pennsylvania School of Medicine Caption Identification of the Epithelial Splicing Regulatory Proteins (ESRPs) in a firefly luciferase-based high throughput cDNA expression screen. Tissue culture plates containing cDNAs placed separately in individual wells were used to screen cells containing the splicing reporter (top). cDNAs that entered the cells and caused the reporter to switch splicing produced firefly luciferase (Luc). One of the wells that "glowed" contained a cDNA for one of the ESRPs, leading to its identification. A blow up of this well is shown at the bottom with a schematic presentation of a cell containing the reporter. A cDNA for ESRP (boxed) entered the cell nucleus (light blue) and was transcribed into ESRP protein (oval). When ESRP enhanced the splicing of an exon (red), the resulting mRNA produced luciferase protein in the cytoplasm of the cell. Credit Russ P. Carstens, M.D., University of Pennsylvania Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.