Sentinel of the Cell (IMAGE) Harvard Medical School Caption Scientists have deciphered the structural and functional differences of a critical human protein that guards against cancer and bacterial and viral infections. The findings explain what sets the human form of the protein apart from this of other mammals. Credit Wen Zhou, Harvard Medical School 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.