C3d (IMAGE) Michigan Medicine - University of Michigan Caption When the C3d vaccine was added to a tumor, the cancer cells began to die (right). Tumor cells not given the vaccine continued to grow. Credit Michigan Medicine Usage Restrictions for use in stories about this research 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.