Perforin-mediated cytolysis. An NK cell possessing the PRF1 A91V/pLOF genotype is activated upon recognition of its target cell, resulting in cytolytic granule exocytosis. Perforin is released along with granzyme to the immunologic synapse between the cells for perforin to form a pore/channel between the cells, which allows for for granzyme delivery triggering apoptosis of the target cell. Figure created with BioRender via subscription to the University of Alabama at Birmingham.