Infiltration (IMAGE) Weizmann Institute of Science Caption Cancer-killing T cells (green) in heterogeneous (l) and homogeneous (r) melanoma tumors. In the heterogeneous tissue, the T cells remained outside the tumor, while in the homogeneous tissue they penetrated to the core Credit Weizmann Institute of Science 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.