Stat3 as Tumor Suppressor (IMAGE) Harvard Medical School Caption In other subtypes of glioblastomas, Stat3 functions as a tumor suppressor gene. In the tissue samples above, the cancer has lost the tumor-suppressor PTEN, leaving that function almost entirely up to Stat3. In the left-hand image, an active Stat3 holds the cancer at bay. But when Stat3 is lost, as shown in the image on the right, the tumor grows. Credit 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.