Protein Subunits (image) Indiana University Caption Protein subunits 9a and 9b found in the mustard plant Arabidopsis thaliana by IU biologists play a role in how different RNA polymerases work, including performing RNA-directed DNA methylation. Altered DNA methylation is involved in genetic disorders and diseases that include cancer. Credit Indiana University Usage Restrictions None 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.