Cells Targeting (IMAGE) University of California - Santa Barbara Caption In an image taken through a microscope, cells containing a CDI system (green) kill target cells (red). The blue cells lack the protein necessary to import the toxins. Credit Courtesy Photo 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.