Molecular Diversity (image) Virginia Tech Caption In this image of mouse brain tissue containing human brain tumor cells, red dye shows invasive, stem-like cells that carry two copies of chromosome 7, while green dye depicts non-stem-like cells that carry three copies of the problematic chromosome. The cells can change into one another by adding or deleting copies of of chromosome 7. Mathematical modeling suggested the involvement of chromosome instability helps tumor cells fend off treatment. Credit Yi-Hong Zhou/University of California-Irvine 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.