SA-4-1BBL Image (IMAGE) University of Louisville Caption A confocal microscope image shows the SA-4-1BBL (green color) bound to its receptor on an immune cell (red color) to initiate an immune activation cascade to fight cancer. Credit University of Louisville 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.