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. Image courtesy University of Louisville.

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. Image courtesy University of Louisville.

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. Image courtesy University of Louisville.

Haval Shirwan, Ph.D.