Cancer Cell Metabolism Kills (IMAGE) University of Helsinki Caption Scientists have discovered that low levels of ATP make cancer gene expressing cells suicidal. Declining ATP levels activate a cellular energy sensor AMPK, which adds a phosphate group to tumor suppressor protein p53, extending the protein's lifetime. This form of p53 moves to mitochondria to activate a cell death protein Bak, which renders cells sensitive to apoptosis. In this immunofluorescence microscope image of cancer gene Myc expressing cells, active death protein Bak appears as green spots localizing on the surface of the mitochondria. The blue staining marks the cell nuclei. Credit Juha Klefstrom Research Group / University of Helsinki Usage Restrictions The image may only be used with appropriate caption and credit. 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.