IRK On and Off (IMAGE) University of California - Riverside Caption These are Arabidopsis root tip cells stained with a red dye. Image on the right shows increased cell division when IRK is inhibited. Credit Jaimie Van Norman / UCR 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.